Optimal design of viscoelastic dampers using eigenvalue assignment   总被引：1，自引：0，他引：1  

Sang‐Hyun Lee  Dong‐In Son  Jinkoo Kim  Kyung‐Won Min 《地震工程与结构动力学》2004,33(4):521-542

In this study a procedure for determining the optimum size and location of viscoelastic dampers is proposed using the eigenvalue assignment technique. Natural frequencies and modal damping ratios, required to realize a given target response, are determined first by the convex model. Then the desired dynamic structural properties are realized by optimally distributing the damping and stiffness coefficients of viscoelastic dampers using non‐linear programming based on the gradient of eigenvalues. This optimization method provides information on the optimal location as well as the magnitude of the damper parameters. The proposed procedure is applied to the retrofit of a 10‐story shear frame, and to a three‐dimensional structure with an asymmetric plan. The analysis results confirm that the responses of model structures retrofitted by the proposed method correspond well with the given target response. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

西准噶尔紫苏花岗岩成因岩石学研究   总被引：8，自引：1，他引：8  

张立飞  冼伟胜  孙敏 《新疆地质》2004,22(1):36-42

紫苏花岗岩呈岩体形式侵入于石炭纪地层中．又为碱长花岗岩侵入．紫苏花岗岩由斜方辉石、单斜辉石、铁橄榄石、条纹长石、石英组成．以正εNd为特征(εNd= 4．8- 5．8)矿物组成、结构和野外产状表明：这些紫苏花岗岩是火成成因的．温压计算估测其结晶条件是T=700～800℃，P=420～575kPa．紫苏花岗岩中有小的富云母包体和巨大的条带状捕虏体．前被认为是残留体，后与其围岩．火山碎屑岩相当．残留体中较低的εNd正值(εNd= 2．6- 3．5)要求新生的下部地壳是紫苏花岗岩的主要源岩：来自这些源岩的紫苏花岗岩的母岩浆在结晶前与一些来自于亏损地幔中的融体混合．该地区体积巨大的碱性花岗岩可能也来自相同的岩浆源，只不过它是在较浅的地壳深度上结晶的．  相似文献   

基于扫描法在复杂地层剖面图绘制中的应用     

魏敏  黄地龙  邓飞 《新疆地质》2004,22(1):104-106

论述了基于扫描线填充算法的理论和适用填充剖面图的数据结构．同时应用该算法采用Delphi和OpenGL绘制了某地质工程实例的二维、三维复杂地质填充剖面图，并取得了较好效果．  相似文献   

重庆石碗溪小流域坡度和高程对土地利用及经济发展的影响   总被引：21，自引：3，他引：21  

罗云云  李瑞雪  屈明 《山地学报》2004,22(2):254-258

坡度和高程是土地资源固有的两个重要环境因子,与土地利用关系密切,尤其是在山区,坡度和高程基本上决定了土地利用的方向和方式,从而影响农业和经济的发展。石碗溪小流域面积20.73km2,为丘陵低山区。按坡度和高程对土地利用的影响程度,把坡度和高程各分为3级,即:0°～15°、15°~25°、>25°和500m以下、500~800 m、800m以上。从1:10 000地形圈上提取土地坡度和高程分级图,与土地利用现状图又叠加,获取各坡度、高程级及其土地利用类型和数据。结果表明,土地面积随坡度、海拔级的增加而加大。耕地分布在各个高程级0～15°的缓坡上,800m以上地区面积最大,果园和森林大多分布在800m以上>25°的陡坡地上。通过分析比较小流域各个行政村2002年农业总收入及种植业、林业、牧业收入与坡度和高程的关系,可以看出坡度和高程对经济发展的影响。最后,根据坡度和高程状况,结合小流域社会经济条件,提出几点建议,以其为山区小流域土地可持续利用及经济持续发展提供科学依据。  相似文献   

中国兴凯湖北岸平原晚全新世花粉记录及泥炭沼泽形成   总被引：7，自引：1，他引：7  

张淑芹  邓伟  阎敏华  李小强  王升忠 《湿地科学》2004,2(2):110-115

通过兴凯湖北岸平原泥炭剖面高分辩率花粉分析研究，对晚全新世花粉划分4个组合带。XKH-4组合时期(1857～1746aB．P．)为沼泽发育前期，这一时期花粉浓度小，陆生草本植物占优势，气候干冷。XKH-3组合时期(1746～1287aB．P．)为沼泽发育早期，这一时期花粉浓度较大，且水生植物花粉含量为剖面最高，喜温落叶阔叶植物大发展时期，气候温和湿润。XKH-2组合时期(1287～602aB．P．)为沼泽发育中期，这一时期花粉浓度最小，但以陆生草本植物为主，木本植物为辅，水生植物急剧减少，针叶植物出现两次高峰，气候向冷干方向发展。XKH-1组合时期(602aB．P．至今)为沼泽发育盛期，这一时期花粉浓度最大，陆生草本植物大发展时期，气候波动较大。  相似文献   

Data Fusion in Distributed Multi-sensor System   总被引：5，自引：0，他引：5  

GUOHang YUMin 《地球空间信息科学学报》2004,7(3):214-217

This paper presents a data fusion method in distributed multi-sensor system including GPS and INS sensors“ data processing. First, a residual X^2-test strategy with the corresponding algorithm is designed.Then a coefficient matrices calculation method of the information sharing principle is derived. Finally, the federated Kalman filter is used to combine these independent, parallel, real-time data. A pseudolite (PL) simulation example is given.  相似文献   

Probabilistic approach for active control of structures: experimental verification     

Jae‐Seung Hwang  Kyung‐Won Min  Sang‐Hyun Lee  Hongjin Kim 《地震工程与结构动力学》2005,34(3):207-225

In our previous study (Earthquake Engineering and Structural Dynamics 2003; 32 :2301), we have developed a probabilistic algorithm for active control of structures. In the probabilistic control algorithm, the control force is determined by the probability that the structural energy exceeds a specified target critical energy, and the direction of a control force is determined by the Lyapunov controller design method. In this paper, an experimental verification of the proposed probabilistic control algorithm is presented. A three‐story test structure equipped with an active mass driver (AMD) has been used. The effectiveness of the control algorithm has been examined by exciting the test structure using a sinusoidal signal, a scaled El Centro earthquake and a broadband Gaussian white noise; and, especially, experiments on control have been performed under different conditions to that of system identification in order to prove the stability and robustness of the proposed control algorithm. The experimental results indicate that the probabilistic control algorithm can achieve a significant response reduction under various types of ground excitations even when the modeling error exists. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Soil respiration in tropical seasonal rain forest in Xishuangbanna, SW China     

SHA Liqing  ZHENG Zheng  TANG Jianwei  Wang Yinghong  ZHANG Yiping  CAO Min  WANG Rui  Liu Guangren  WANG Yuesi  SUN Yang 《中国科学D辑(英文版)》2005,48(Z1)

With the static opaque chamber and gas chromatography technique, from January 2003 to January 2004 soil respiration was investigated in a tropical seasonal rain forest in Xishuangbanna, SW China. In this study three treatments were applied, each with three replicates: A (bare soil), B (soil+litter), and C (soil+litter+seedling). The results showed that soil respiration varied seasonally, low from December 2003 to February 2004, and high from June to July 2004. The annual average values of CO2 efflux from soil respiration differed among the treatments at 1% level, with the rank of C (14642 mgCO2· m-2. h-1)＞B (12807 mgCO2· m-2. h-1)＞A (9532 mgCO2· m-2. h-1). Diurnal variation in soil respiration was not apparent due to little diurnal temperate change in Xishuangbanna. There was a parabola relationship between soil respiration and soil moisture at 1% level. Soil respiration rates were higher when soil moisture ranged from 35% to 45%. There was an exponential relationship between soil respiration and soil temperature (at a depth of 5cm in mineral soil) at 1% level. The calculated Q1o values in this study,ranging from 2.03 to 2.36, were very near to those of tropical soil reported. The CO2 efflux in 2003was 5.34 kgCO2· m-2. a-1 from soil plus litter plus seedling, of them 3.48 kgCO2· m-2. a-1 from soil (accounting for 62.5%), 1.19 kgCO2· m-2. a-1 from litter (22.3%) and 0.67 kgCO2·m-2. a-1 from seedling (12.5%).  相似文献   

Major reactive species of ambient volatile organic compounds (VOCs) and their sources in Beijing   总被引：1，自引：0，他引：1  

SHAO Min  FU Linlin  LIU Ying  LU Sihua  ZHANG Yuanhang  TANG Xiaoyan 《中国科学D辑(英文版)》2005,48(Z2)

Volatile organic compounds (VOCs) are important precursors of atmospheric chemical processes. As a whole mixture, the ambient VOCs show very strong chemical reactivity. Based on OH radical loss rates in the air, the chemical reactivity of VOCs in Beijing was calculated. The results revealed that alkenes, accounting for only about 15% in the mixing ratio of VOCs, provide nearly 75% of the reactivity of ambient VOCs and the C4 to C5 alkenes were the major reactive species among the alkenes. The study of emission characteristics of various VOCs sources indicated that these alkenes are mainly from vehicle exhaust and gasoline evaporation. The reduction of alkene species in these two sources will be effective in photochemical pollution control in Beijing.  相似文献   

GPS观测的2001年昆仑山口西M_S8.1级地震地壳变形   总被引：19，自引：0，他引：19       下载免费PDF全文

任金卫  王敏 《第四纪研究》2005,25(1):34-44

2001年11月14日17时26分,在昆仑山口西青海和新疆交界处发生了M_S8.1级强烈地震。震后利用 GPS开展了相对密集的地壳形变观测。计算获得的同震位移表明,地震地壳形变影响范围大致为88°～97°E, 32°～38°N,断层运动具有明显的左旋兼挤压的特点。在昆仑山口附近GPS观测获得的地表破裂两侧的相对左旋 位移量约为2.6m,与地表野外调查获得的该处的地震破裂位移值符合的很好。断裂南侧垂直断裂走向同震位移 量逐渐衰减,位移方向相对稳定。而断裂北侧,同震位移主要集中分布在柴达木盆地南缘,位移方向变化较大,盆 地内部位移量迅速衰减,表明东昆仑断裂北侧柴达木盆地地壳介质性质与其南侧高原腹地有明显不同。GPS观测 得到的震后断层蠕动结果表明,最初两周内断层蠕动位移量就占了观测期(近1年时间)总位移量的47%还要多, 其后半年多的时间内断层蠕动位移量不到观测期总位移量的40%,而余下的近5个月时间断层蠕动位移量只占观 测期总位移量的13%。断层蠕动速率在最初两周内超过130cm/a,到2002年3月11日迅速下降到26cm/a,其后 则逐渐呈线性衰减。区域GPS观测的初步结果同时表明,尽管地震破裂附近断层两侧有较大的相对位移,但东部 甘青川一带相关断层上相对运动不明显,可能说明这一区域仍处在  相似文献