Fuzzy logic control of bridge structures using intelligent semi-active seismic isolation systems

Passive supplemental damping in a seismically isolated structure provides the necessary energy dissipation to limit the isolation system displacement. However, damper forces can become quite large as the passive damping level is increased, resulting in the requirement to transfer large forces at the damper connections to the structure which may be particularly difficult to accommodate in retrofit applications. One method to limit the level of damping force while simultaneously controlling the isolation system displacement is to utilize an intelligent hybrid isolation system containing semi-active dampers in which the damping coeffic ient can be modulated. The effectiveness of such a hybrid seismic isolation system for earthquake hazard mitigation is investigated in this paper. The system is examined through an analytical and computational study of the seismic response of a bridge structure containing a hybrid isolation system consisting of elastomeric bearings and semi-active dampers. Control algorithms for operation of the semi-active dampers are developed based on fuzzy logic control theory. Practical limits on the response of the isolation system are considered and utilized in the evaluation of the control algorithms. The results of the study show that both passive and semi-active hybrid seismic isolation systems consisting of combined base isolation bearings and supplemental energy dissipation devices can be beneficial in reducing the seismic response of structures. These hybrid systems may prevent or significantly reduce structural damage during a seismic event. Furthermore, it is shown that intelligent semi-active seismic isolation systems are capable of controlling the peak deck displacement of bridges, and thus reducing the required length of expansion joints, while simultaneously limiting peak damper forces. Copyright © 1999 John Wiley & Sons, Ltd.     

Field test of an intelligent stiffener for bridges at the I-35 Walnut Creek bridge

The addition of controllable hardware to structures to mitigate vibration that results from dynamic loads is an emerging area of technological development. The paper describes the results of a research project that was conducted to test a relatively new approach to structural control: an adjustable semi-active hydraulic actuation system that was attached to an in service interstate bridge. The system, which is powered by a 12-volt automative battery, has been tested over a 2- year period. Data indicates that the system reduces truck induced peak stresses by over 50 per cent, and calculations, per NCHRP 299, indicate that the safe life of the structure is increased by approximately 50 yr. The installed cost of the system represents less than 10 per cent of the cost to replace the bridge. Copyright © 1999 John Wiley & Sons, Ltd.     

基于虚拟仪器的水下目标二维角估计

利用LabVIEW软件,通过8通道数据采集卡和均匀圆阵对水下目标的噪声进行采集和处理。结合一维直线阵波束形成理论,实现了对水下目标二维方向角估计实验研究和算法验证。实验证明利用虚拟仪器方便地实现了对水声信号的采集、处理,以及在方位估计时,为传感器布阵和算法的确定提供参考。     

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全站仪在田赛距离测量中的应用

在介绍传统田赛测距方法的基础上,重点研究用全站仪和田赛成绩测量系统测距的方法,分析其使用范围,比较其精度,并得出了有益的结论。     

GPS/DR导航中的智能地图匹配方法研究

探讨了在简单路网区域内GPS/DR导航的智能地图匹配原则和方法,该法不仅能够消除DR的误差累计,提高定位精度,而且试验结果表明,在市郊的路网中匹配良好。     

数字压力式水位仪观测误差与测试方法

数字压力式水位仪误差来源于压力测量误差、水密度取值误差和重力加速度取值误差,其中后两者引起的误差与水柱高度有关。对我国地震井水位观测网的水密度和重力加速度取值误差进行分析,大部分观测井水密度和重力加速度取值误差引起的水位观测误差基本上可以忽略。为了减少仪器的观测误差,水位传感器投放深度不宜过深,水位观测井筒水温不宜过高。对于个别矿化度大、富气泡的观测井和水温较高的非自流井,密度影响不容忽视。最后,对近几年来招标采购的水位仪器的测试情况进行总结,认为采用压力输入法与模拟井孔法相结合来测试压力式水位仪器的观测误差更为科学和准确。     

一种浅水型海流定点观测系统布放方法

介绍了采用座底式轻型仪器架进行30 m以内浅水深海流观测的两种系统布放方法:先锚后仪器架法和先仪器架后锚法。其中,详细介绍了先锚后仪器架法的布放过程,对先仪器架后锚法作了简要介绍。     

IPM在电法发送机上应用时的死区时间选择

IPM是IGBT智能模块的简称,它集功率变换,驱动及保护电路于一身,简化了逆变器外围电路设计,大大缩短了发送机开发周期.而IPM的运用要注意一个很重要的问题：死区时间的设置.在电法勘探发送机中,负载感抗有时比较大,而感抗的大小则会影响到IPM的关断时间.因此要求发送机的死区时间设定范围比较大,同时还要求在不同的发送频率下死区时间可调.如大极距和小极距由于供电回路大小不同而导致的感抗不同就要采用不同的设定值,同时高频时则要求死区时间在满足要求的情况下尽可能的小,否则会引起输出严重失真.综合以上考虑以及硬件实现上的方便性,可将死区时间设定为可调的几档,分别对应不同的勘探方法和不同的使用条件.     

城市商业区智能泊车系统的设计与开发

针对石家庄市商业区停车压力和停车管理系统现状,基于运动车辆的当前位置、车库中的车位数量、道路状况、路口限制等动态约束因子,进行了智能泊车系统的技术设计与软件开发。通过建立复杂约束条件下的模糊预测模型,并使用扩展和改进后相邻节点低值传递的最短路径引导算法,实现了城市商业区泊车过程中动态最短路径与最佳路径的分析与可视查询,并介绍了模拟应用情况。