Experimental performance evaluation of an equipment isolation using MR dampers     

Yu‐Cheng Fan  Chin‐Hsiung Loh  Jann N. Yang  Pei‐Yang Lin 《地震工程与结构动力学》2009,38(3):285-305

Critical non‐structural equipments, including life‐saving equipment in hospitals, circuit breakers, computers, high technology instrumentations, etc., are vulnerable to strong earthquakes, and the failure of these equipments may result in a heavy economic loss. In this connection, innovative control systems and strategies are needed for their seismic protections. This paper presents the performance evaluation of passive and semi‐active control in the equipment isolation system for earthquake protection. Through shaking table tests of a 3‐story steel frame with equipment on the first floor, a magnetorheological (MR)‐damper together with a sliding friction pendulum isolation system is placed between the equipment and floor to reduce the vibration of the equipment. Various control algorithms are used for this semi‐active control studies, including the decentralized sliding mode control (DSMC) and LQR control. The passive‐on and passive‐off control of MR damper is used as a reference for the discussion on the control effectiveness. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

希尔伯特-黄变换在地震资料处理中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

刘庆敏  杨午阳  李书平  何欣 《地震工程学报》2009,31(3):211-216

希尔伯特-黄变换是最新发展起来的处理非线性非平稳信号的时频分析方法.本文介绍了该方法的基本原理和几个关键技术,以及其优势所在,并将它应用于含随机噪音的地震信号和实际地震资料的分解.分解后的信号能够重构原始信号,重构后在信噪比和分辨率方面有了一定的提高,对地震资料的去噪有重要意义.  相似文献   

运用测井信息研究烃源岩进展及其资源评价意义   总被引：9，自引：1，他引：8       下载免费PDF全文

闫建平  蔡进功  赵铭海  郑德顺 《地球物理学进展》2009,24(1):270-279

运用测井信息评价烃源岩自开始以来已取得了长足进步,从定性的分析、识别发展到现在可定量计算地化指标,为克服因取芯不足而在区域范围内进行资源评价的难题创造了有利条件,烃源岩中有机质、粘土矿物是影响其测井响应的两个重要变量,测井对岩石中有机质和粘土矿物的类型、丰度、压实程度及富集状态不同而产生的岩石物理、电化学性质的差异,是利用测井信息识别和评价烃源岩的基础,随着油气勘探形势的严峻,烃源岩的测井研究将向更深层次的方向发展,烃源岩的地球化学特征与测井响应特征对应关系的机理研究、发展利用电化学性质进行烃源岩评价的方法、进行烃源岩的岩石物理实验与测井数值模拟将是今后开展烃源岩测井评价研究的新方向.  相似文献   

GRAPES全球非静力大气模式的正规模分析   总被引：1，自引：0，他引：1       下载免费PDF全文

王光辉  沈学顺  胡江林  陈峰峰 《地球物理学报》2009,52(12):2964-2972

为分析数值模式动力学框架中不同波动的特性及对数值天气预报模式计算稳定性的影响,文章对GRAPES（Global/Regional Assimilation and PrEdiction System）全球非静力大气模式进行了正规模分析.首先,建立了静止大气状态下模式的线性化系统,并在适当的边界条件下将线性化系统分解成具有垂直与水平结构方程的本征值、本征函数耦合问题.然后在等温大气条件下,利用耦合问题的数值结果分析得出：GRAPES非静力模式除了有几乎和对应的静力模式一致的向东、向西传播的重力惯性波及向西传播的Rossby波外,还有一个向东、向西传播的声惯性波;特别是,只有当纵横比较大时,非静力模式对重力惯性波才会有显著影响.  相似文献   

冬季北太平洋优势气候模态的转移     

吕庆平  张立凤  张铭 《气候变化研究进展》2016,12(6):494-499

采用EOF分解和小波分析,并引入相似度,分析冬季北太平洋的两个主要气候模态,即太平洋年代际振荡（PDO）模态与北太平洋涡旋振荡（NPGO）模态,及其结构特征随时间的演变。结果表明：1988/1989年的气候转移后,冬季海温距平（SSTA）优势模态为NPGO模态的年份越来越多,这种优势气候模态的转移现象表现出准18 a的年代际周期;SSTA与NPGO模态相似度的20年滑动平均在20世纪80年代中后期之后超过了SSTA与PDO模态的相应值,这表明此后SSTA的优势模态发生了转移,由PDO型转换为NPGO型;对典型时间段SSTA的合成分析显示,其优势模态由1988年前的PDO型转变为之后的NPGO型。  相似文献   

Development of deformable connection for earthquake‐resistant buildings to reduce floor accelerations and force responses          下载免费PDF全文

Georgios Tsampras  Richard Sause  Dichuan Zhang  Robert B. Fleischman  Jose I. Restrepo  David Mar  Joseph Maffei 《地震工程与结构动力学》2016,45(9):1473-1494

This paper presents the development of a deformable connection that is used to connect each floor system of the flexible gravity load resisting system (GLRS) with the stiff lateral force resisting system (LFRS) of an earthquake‐resistant building. It is shown that the deformable connection acts as a seismic response modification device, which limits the lateral forces transferred from each floor to the LFRS and allows relative motion between the GLRS and LFRS. In addition, the floor accelerations and the LFRS story shears related to the higher‐mode responses are reduced. The dispersion of peak responses is also significantly reduced. Numerical simulations of the earthquake response of a 12‐story reinforced concrete shear wall example building with deformable connections are used to define an approximate feasible design space for the deformable connection. The responses of the example building model with deformable connections and the example building model with rigid‐elastic connections are compared. Two configurations of the deformable connection are studied. In one configuration, a buckling restrained brace is used as the limited‐strength load‐carrying hysteretic component of the deformable connection, and in the other configuration, a friction device is used. Low damping laminated rubber bearings are used in both configurations to ensure the out‐of‐plane stability of the LFRS and to provide post‐elastic stiffness to the deformable connection. Important experimental results from full‐scale tests of the deformable connections are presented and used to calibrate numerical models of the connections. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

直接基于位移设计的高强钢组合K形偏心支撑钢框架的抗震性能研究          下载免费PDF全文

郑晓伟  苏明周  石鲁  秦瑞  王迪涛  王喆 《地震工程学报》2016,38(5):678-684

K形高强钢组合偏心支撑(K-HSS-EBF)是指耗能连梁和支撑采用Q345钢,而框架梁、框架柱采用高强度钢(如Q460)。为研究其在罕遇地震作用下的抗震性能,在试验研究的基础上,采用直接基于位移的抗震设计方法设计了5层、8层和12层算例,分别进行静力推覆分析和动力弹塑性分析,研究高强钢组合偏心支撑钢框架在罕遇地震作用下层间侧移分布和破坏模式。研究结果表明:直接基于位移的抗震设计方法设计的算例在罕遇地震作用下,结构的层间侧移满足我国现行抗震规范的要求,结构呈理想的渐进式梁铰屈服机构,并证明该设计方法的合理性和可靠性。  相似文献   

Thresholds,mode switching,and emergent equilibrium in geomorphic systems          下载免费PDF全文

Jonathan D. Phillips 《地球表面变化过程与地形》2014,39(1):71-79

Landform and landscape evolution may be convergent, whereby initial differences and irregularities are (on average) reduced and smoothed, or divergent, with increasing variation and irregularity. Convergent and divergent evolution are directly related to dynamical (in)stability. Unstable interactions among geomorphic system components tend to dominate in earlier stages of development, while stable limits often become dominant in later stages. This results in mode switching, from unstable, divergent to stable, convergent development. Divergent‐to‐convergent mode switches emerge from a common structure in many geomorphic systems: mutually reinforcing or competitive interrelationships among system components, and negative self‐effects limiting individual components. When the interactions between components are dominant, divergent evolution occurs. As threshold limits to divergent development are approached, self‐limiting effects become more important, triggering a switch to convergence. The mode shift is an emergent phenomenon, arising from basic principles of threshold modulation and gradient selection. As an example, the relationships among flow concentration, erosive force, and channel incision in fluvial systems are examined in the context of mode switching and thresholds. The commonly observed divergence in channel growth and fluvial dissection and network development, eventually transitioning to a stable, convergent configuration, is an emergent outcome of gradient selection and threshold modification, and does not imply any goal functions of balancing mass fluxes or limiting change. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

豫西地形对一次强降水过程的影响分析     

张宁  苏爱芳 《气象与环境学报》2014,30(6):16-24

利用中尺度模式WRF 3.3.1模拟了2007年7月29日豫西山区强对流天气过程,并进行了地形高度敏感性试验。结果表明：模式能够很好地再现此次强对流降水过程,模拟降水范围与强降雨中心均与实况较一致。分析对比控制试验和地形敏感性试验结果可知,地形的改变能够在水平和垂直方向上影响环流形势,进而影响降水的落区和中心量级。地形升高和迎风坡梯度增大使近地面层水平风场辐合增强,中层上升运动明显增大,且低层的水汽通量增大,导致雨带横向范围和降水中心量级明显增大;而地形降低和迎风坡梯度减小使山脉对近地面层气流的阻挡作用明显减弱,低层水汽通量显著降低,中层辐合抬升运动明显减弱,迎风坡前强降水中心减弱甚至消失,而山脉下游降水则有所增强。分析地形高度与山前降水的定量关系可知,降水中心量级随着地形升高或降低相应地增大或减小,但二者并非完全的线性正相关。  相似文献   

A steady nonlinear and singular vortex Rossby wave within a rapidly rotating vortex. Part I: Theory     

P. Caillol 《地球物理与天体物理流体动力学》2014,108(4):387-436

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