顾功叙

某车站,一队人员正在等待SEG(美国勘探地球物理工作者协会)的往返列车前往美国的阿纳海姆会谈中心。该队人员包括由中国学生组成的3名代表,1名展览人员,名义会员顾功叙以及他的夫人,另外还有1名SEG的职员。除此外,这里呈现的完全是普通公交车站的情形。开始的时候,大家好像达成     

秦岭龙之脉

我幻想有一天登上秦岭的最高峰太白山山顶,伸开双臂宣布,我的左手在中国的南方,我的左手在中国的北方。我也幻想有一天可以到秦岭的终南山,寻找那传说中终南山后的活死人墓,看看是否还有神雕大侠和小龙女的后人在练着玉女素心剑法。我更幻想如果可以"穿越",我要回到200万年前的秦岭,游走在那寒冷的第四冰川期,和我们的祖先一起在秦岭的南北间穿行。     

城市抗震防灾规划的研究与展望

抗震防灾规划是提高城镇综合抗震能力的有效措施之一,与城市总体规划一并实施.重点回顾了我国抗震防灾规划工作的发展历程,同时对美国、日本在建立防灾规划方面的情况也进行了介绍.通过编制城市的抗震防灾规划,加强城市的综合抗震防灾能力,在丽江地震中被证明是一个有效的手段.综述了在这个方面的发展与变化,并就未来的可能的发展方向作了总结与展望,以期国内外同仁进一步研究.     

太湖西南部河流流域的营养盐排放

以MONERIS河流系统模型为基础,建立了由农业土地营养盐平衡模型、流域营养盐排放模型及河道营养盐滞留模型3个模型组成的模型系统.该系统被用来计算太湖西南部河流流域的营养盐排放量.利用实测的河流系统的负荷数据,对模型系统进行验证.验证结果表明,N、P计算负荷与实测负荷的偏差分别在10%及30%以内.利用该系统,对1992-1996年及1997-2001年间的营养盐排放量进行计算.计算结果表明,1997-2001年间的氮的年平均排放量为5646 t/a,该排放量比前5年的年均排放量减少827 t/a.从磷的排放量来看,1997-2001年间的年排放量为554 t/a,比前5年的均值减少45 t/a.分析结果表明,与1992-1996年相比,1997-2001年间的点源排放量及农业土地营养盐剩余量的减少是流域营养盐排放量减少的主要原因.     

2008年度日本防灾对策的重点

为实现防灾、减灾的社会,在进一步促进平日防灾对策的同时,从推进具体的战略、根据灾害特性采取各种对策的观点,中央防灾会议2007年6月21日决定,2008年度实施以以下8个项目为重点的防灾对策。1树立减轻大规模灾害的战略思路(1)首都直下型地震以及大规模地震的不断准备。(2)推动大规模水灾对策。为了把任何时间任何地方发生的大地震所造成的灾害控制在最低限度,在正确抓住地震防灾战略进展情况的同时,要加强实现以减灾为目标的各种对策。其中,为确保国家中枢机能的连续性,特别是需要对首都直下型地震采取对策,要推进中央省厅、企业等制定业务…     

霍尔果斯泥火山活动与新疆地区中强以上地震活动关系的初步研究

基于1991-2006年间对新疆霍尔果斯泥火山的系统观测,初步发现了泥火山活动与新疆地区中强以上地震的活动具有较好的对应关系,且对预测未来地震的发震时间及震级都有一定的指导意义,如能对泥火山的动态进行长期监测,会得到更加有研究意义的资料; 并认为泥火山具有一定的映震性能的原因可能与该泥火山处于中强以上地震活动的近震源区、构造上处于霍尔果斯背斜轴部及泥火山物质来自地层相对深处等有关.     

采用Ernst公式计算斜拉桥拉索振动特性的精度分析

斜拉桥拉索的动力特性是建立在斜拉桥的静力分析的基础上的.在静力分析中,几何非线性明显的索经常通过Ernst公式线性化成二力杆,但是,在动力分析中,很少有人研究过Ernst公式的精度.编制了基于弹性悬链线单元的斜拉索的非线性有限元分析程序,该程序可以一根索的任何一个参数值为已知条件来确定索的状态,研究了斜拉索不同张拉阶段索的频率和振型特性,并比较了Ernst公式计算拉索动力特性的精度和适用范围.     

介质的磁化率与包裹体浓度的关系

在第五卷第一期的地球物理学报上,我们曾讨论介质的磁化率与包裹体形状的关系,但是对于介质磁化率与包裹体浓度的关系没有详细讨论。在本文中,将根据巳知的材料,对这个问题加以讨论,作为“介质的磁化率与包裹体形状的关系”一文的补充。     

浅海海洋盐度、温度和深度调查的精确度与海水密度计算的关系

一、本文目的海水密度系海水的盐度、温度和压力的连续函数,而在海水的压力每增加1分巴值深度几增加1米的极近似情况下,海水密度即系海水的盐度、温度和深度的连续函数。在必须精确获知海水密度值的要求下,海水的密度是藉它与盐度、温度和压力三者的函数关系计算而得的。为了要使计算所得的海水密度值有一定的精确度,所以海洋盐度、温度和深度调查的精确度就必须有一定的要求。由於中国海皆系浅海,所以本文仅就浅海海洋盐度、温度和深度调查的精确度与海水密度计算的关系加以论述。     

武汉月湖水生植被重建过程中浮游植物的动态变化

2004年12月-2005年5月武汉市月湖水生植被重建过程中,对浮游植物进行逐月调查.结果表明,在营养盐浓度较高的条件下,浮游植物仍保持较低的生物量和密度,浮游植物的生长与温度保持一定的相关性,但与湖水营养盐浓度并不存在相关关系.菹草和伊乐藻能使水体的透明度保持较高的状态.浮游植物主要由隐藻和硅藻组成,能形成水华的一些常见种类并未随温度升高而出现,可能与这两种沉水植物的存在改变了浮游植物的群落结构有关.因此,在水温较低的冬季和春季进行水生植被重建是富营养化湖泊治理的有效途径.     

基于市场机制结构控制策略的研究和应用进展

半主动控制装置以其廉价、耗能低及控制稳定性好的优势成为目前结构控制领域的研究热点,由此势必产生具有大量半主动控制装置形成的复杂的结构控制系统,但足对于由大量半主动控制装置组成的结构控制系统,其形式非常复杂。相比于传统的集中式控制策略,分布式控制策略更适应此类复杂系统的控制要求。而基于市场机制的控制策略（Market-basedControl,简称MBC）属于分布式控制策略,它利用市场来模拟复杂的控制系统,用销售商和消费者来代替控制器和能源输出,从而将整个控制系统离散化,利用自由市场经济对有限资源合理分配的特点,对结构的振动实施高效的控制。介绍了分布式控制的概念,回顾了基于市场控制理论的发展过程,重点介绍丁其在土木工程领域的应用,存在的问题及未来发展方向。     

ACTIVE AND SEMI-ACTIVE CONTROL OF STRUCTURES UNDER SEISMIC EXCITATION

Considerable effort has been devoted to develop passive and active methods for reducing structural response under seismic excitations. Passive control approaches have already found application in practice. Active control methods, on the other hand, are being vigorously examined for application to civil structures. This paper investigates the application of active and semi-active control schemes to structures subjected to seismic excitations, and it focuses on the use of the sliding-mode control approach for the development of the control algorithms. The possibility of control redundancy with respect to the number of sliding constraints is taken into account in the controller design. Several sets of numerical results are obtained for a realistic 10-storey shear building, subjected to earthquake-induced ground motions and controlled by active or semi-active control schemes. It is observed that both active and semi-active control schemes can be used to reduce the dynamic response. Active control performs very effectively in reducing the structural response, but the required control force values can be quite large to limit its practical application in the case of large and massive buildings. Active regulation of linear viscous dampers was found unnecessary for this type of structural system, as it did not induce any significantly more reduction in the response than the dampers acting passively. On the other hand, it is shown that active regulation of stiffness can be used with advantage to reduce the response. © 1997 by John Wiley & Sons, Ltd.     

结构控制技术在桥梁工程中的应用综述

就桥梁结构的被动控制和主动控制以及控制算法等三方面,系统综述了桥梁工程中振动控制技术的应用现状与进展,总结了桥梁结构主、被动控制所取得的一些研究成果和结论,同时,指出目前研究工作中存在的尚待进一步完善的问题,提出了今后的研究方向。     

A Self-tuning Robust Control System for nonlinear real-time hybrid simulation

In a real-time hybrid simulation, a transfer system is used to enforce the interface interaction between computational and physical substructures. A model-based, multilayer nonlinear control system is developed to accommodate extensive performance variations and uncertainties in a physical substructure. The aim of this work is to extend the application of real-time hybrid simulation to investigating failure, nonlinearity, and nonstationary behavior. This Self-tuning Robust Control System (SRCSys) consists of two layers: robustness and adaptation. The robustness layer synthesizes a nonlinear control law such that the closed-loop dynamics perform as intended under a broad range of parametric and nonparametric uncertainties. Sliding mode control is employed as the control scheme in this layer. Then, the adaptation layer reduces uncertainties at run time through slow and controlled learning of the control plant. The tracking performance of the SRCSys is evaluated in two experiments that have highly uncertain physical specimens.     

Performance-based semi-active control algorithm for protecting base isolated buildings from near-fault earthquakes

Base isolated structures have been found to be at risk in near-fault regions as a result of long period pulses that may exist in near-source ground motions.Various control strategies,including passive,active and semi-active control systems,have been investigated to overcome this problem.This study focuses on the development of a semi-active control algorithm based on several performance levels anticipated from an isolated building during different levels of ground shaking corresponding to various earthquake hazard levels.The proposed performance-based algorithm is based on a modified version of the well-known semi-active skyhook control algorithm.The proposed control algorithm changes the control gain depending on the level of shaking imposed on the structure.The proposed control system has been evaluated using a series of analyses performed on a base isolated benchmark building subjected to seven pairs of scaled ground motion records.Simulation results show that the newly proposed algorithm is effective in improving the structural and nonstructural performance of the building for selected earthquakes.     

分散滑移模态控制法在高层建筑结构抗震中的应用

分散控制与集中控制策略相比可以提高结构控制系统的可靠性。文中将分散控制和滑移模态控制算法原理相结合,导出分散滑移模态控制(decentralized sliding mode control,DSMC)算法并应用于高层结构振动控制中。该方法是将结构分解为若干个子结构,分别进行滑移模态控制。文中以某20层钢结构Benchmark模型为例,分别进行3个子结构与4个子结构的分散控制数值计算,与线性二次型最优控制(Linear quadratic optimal control,LQR)效果相比,DSMC算法可以有效地抑制结构位移和加速度反应。     

A Semi-active Oleodynamic Damper for Earthquake Control. Part 2: Evaluation of Performance through Shaking Table Tests

Sine sweep and earthquake excitation tests have been performed on a one-story spatial steel frame building equipped with two identical semi-active assemblies described and fully characterized in a companion paper. The tests allowed identifying and validating simple mathematical models of the building in its passive configurations as well as in semi-active operation according to an energy storing and suddenly dissipating algorithm. In order to eliminate or at least attenuate the detrimental effects of control delays due to adopted software, electronic apparatus and mechanical inertia of variable dampers' moving parts, a simple ‘sine-fit’ prediction method was conceived, evaluated and adopted in subsequent tests. It is shown that, with adequate anticipation of device operation, the selected control algorithm produces a satisfactory reduction of building response compared to that obtained in passive configurations, with overall system efficiency practically independent of the earthquake input and related only to the properties of the semi-active assembly. This revised version was published online in July 2006 with corrections to the Cover Date.     

主动变刚度阻尼多振型半主动控制研究

探讨了开关型半主动控制算法的研究现状,基于单步状态预测控制律,提出了针对高层建筑多自由度结构体系AVS/D(主动变刚度阻尼)多振型开关控制律。通过算例仿真分析与其它开关控制律作了比较,结果表明这种开关控制律是可行的、有效的。特别是在多自由度结构体系振动过程中有多个振型同时在受控结构的反应中起主要作用时,本文提出的开关控制律比其它振型开关控制律有更好的控制效果。     

双向偏心结构扭转耦联地震反应的序列最优控制

本文分析了不对称建筑结构平移-扭转耦联振动的动力特性及地震作用下的响应;根据地震动输入结构的过程,推导出一种更为一般的最优控制算法,所获得的控制力表达式同时包括地震响应和地震激励。通过对一非规则四层框架结构的扭转耦联地震反应控制分析表明,该算法不仅能有效地控制结构的平移地震反应,而且更有效地抑制结构的扭转耦联地震反应。     

Reliability‐based robust control for uncertain dynamical systems using feedback of incomplete noisy response measurements

A reliability‐based output feedback control methodology is presented for controlling the dynamic response of systems that are represented by linear state‐space models. The design criterion is based on a robust failure probability for the system. This criterion provides robustness for the controlled system by considering a probability distribution over a set of possible system models with a stochastic model of the excitation so that robust performance is expected. The control command signal can be calculated using incomplete response measurements at previous time steps without requiring state estimation. Examples of robust structural control using an active mass driver on a shear building model and on a benchmark structure are presented to illustrate the proposed method. Copyright © 2003 John Wiley & Sons, Ltd.