外差式激光干涉仪应用于正弦直线和旋转振动测量技术的研究

介绍外差式激光干涉仪和应用于旋转振动测量的衍射光栅技术理论和工作原理。针对马赫-泽德外差式激光干涉仪在绝对法振动校准技术中的应用，简要介绍了测量系统另外两个重要组成部分（频移变换和数字信号处理）的原理、算法和技术实现。这种振动测量系统与正弦直线和旋转激振系统相配合，采用同一种正弦逼近的信号处理方法，可实现直线振动量（位移、速度、加速度）和旋转振动量（角位移、角速度、角加速度）两大类型、各种振动传感器幅相特性绝对法的精确校准。     

Walking-Induced Floor Vibration Case Studies

Excessive floor vibration due to walking is an important serviceability condition to be considered in building design. This paper presents several case studies of problem floors. The case studies include complaints about office, classroom, and retail spaces where vibration levels were found disturbing. In each of these cases, the cause of the vibration was due to people walking around the space. These case studies are presented to reinforce the existence of this problem, to describe nonstructural factors that affect the behavior of floors, and to provide new data to the design and research communities.     

Wavelet-Hybrid Feedback Linear Mean Squared Algorithm for Robust Control of Cable-Stayed Bridges

Cable-stayed bridges are flexible structures, and control of their vibrations is an important consideration and a challenging problem. In this paper, the wavelet-hybrid feedback least mean squared algorithm recently developed by the writers is used for vibration control of cable-stayed bridges under various seismic excitations. The effectiveness of the algorithm is investigated through numerical simulation using a benchmark control problem created based on an actual semifan-type cable-stayed bridge design. The performance of the algorithm is compared with that of a sample linear quadratic Gaussian (LQG) controller using three different earthquake records: the El Centro (California, 1940), Mexico City (Mexico, 1985), and Gebze (Turkey, 1999) earthquakes. Simulation results demonstrate that the new algorithm is consistently more effective than the sample LQG controller for all three earthquake records. Additional numerical simulations are performed to evaluate the sensitivity of the new control algorithm. It is concluded that the algorithm is robust against the uncertainties existing in modeling structures.     

Free Vibration Analysis of Laminated Stiffened Shells

The free vibration of the laminated composite anticlastic doubly curved stiffened shells is investigated using the finite element method. The stiffened shell element is obtained by appropriate combination of the nine-node doubly curved isoparametric thin shallow shell element with the three-node curved isoparametric beam element. The shell forms include the hyperbolic paraboloid, hypar, and conoidal shells. The accuracy of the formulation is validated by comparing the authors’ results of specific problems with those available in the literature. The additional problems are taken up for parametric studies to include the effects of fiber orientation and lamina stacking sequence of shells and stiffeners. Moreover, the effects of number, types, and orientations of stiffeners, and stiffener depth to shell thickness ratio on the fundamental frequency are also included in the present study. Further, mode shapes corresponding to the fundamental frequency for typical cases are obtained to verify the parametric trend of the results of the fundamental frequency.     

Damping of Cables by a Transverse Force

A general asymptotic format is presented for the effect on the modal vibrations of a transverse damper close to the end of a cable. Complete locking of the damper leads to an increase of the natural frequencies, and it is demonstrated that the maximum attainable damping is a certain fraction of the relative frequency increase, depending on the type of damping device. The asymptotic format only includes a real and a complex nondimensional parameter, and it is demonstrated how these parameters can be determined from the frequency increase by locking and from an energy balance on the undamped natural vibration modes. It is shown how the asymptotic format can incorporate sag of the cable, and specific results are presented for viscous damping, the effect of stiffness and mass, fractional viscous damping, and a nonlinear viscous damper. The relation of the stiffness component to active and semiactive damping is discussed.     

INMO结晶器液压振动控制系统

介绍了攀钢2#板坯连铸结晶器振动控制系统,对系统的组成、功能、调节原理及运行作了简要阐述。振动设备采用达涅利公司开发的结晶器液压振动系统(INMO系统),具有振动质量小,振幅、频率和振动波形可调整的特点,从而改善了铸坯表面与结晶器铜壁的润滑效果,减少振痕深度,提高铸坯表面质量,并减少粘结漏钢。     

A system for powder transport based on piezoelectrically excited ultrasonic progressive waves

The transport and dosage of granular materials are an important part of Process Engineering. Thereby, the food, chemical, pharmaceutical and coating industries set high demands on the transport and dosage performances of the used plants. In this context, Ultrasound Process Technology in the past years has developed itself into an attractive alternative compared to presently used classical technologies.

This paper describes the application of ultrasonic progressive waves in a powder-feeding device. The use of a specific pipe material with appropriate damping characteristics allows to generate a progressive wave using a single piezoelectric actuator. Small objects can be carried along the surface of a pipe by the elliptic motion at the surface, which is the result of a flexural progressive wave. The operational principle is the same as in travelling wave ultrasonic motors.

It was experimentally confirmed that the device can be used for feeding and supplying small amounts of powder. The powder-fed performance, however, strongly depends on environmental conditions, so that a control of the system is required. Construction and characteristics of a trial device are shown.     

SPVT系统的框架结构研究

目前,由物理模型、数值方法和可视化技术相结合而发展起来的仿真技术,受到广泛的重视,正在迅速发展.在振动工程界,利用计算机技术将振动试验与计算机仿真技术集成在一起也是一个追求的目标.虚拟振动仿真系统SPVT（Simulation Platform of Vibration Test）,是在对振动环境试验和振动环境试验的数值仿真分析的研究基础上,研制的具备试验项目管理、数据信息处理、试验控制、振动分析、夹具设计、模型修正、试验再现等多种功能的集成化系统.该系统基于分布式异构网络,以项目管理为核心,实现仿真自动化,为振动环境试验的发展探索出一种试验与计算机仿真相结合、相互促进的新途径.该文介绍了系统的框架结构和实现该结构的关键技术.     

SR电机电压斩波方式电磁力分析

本文基于SR电机线性模型和定子振动简化模型 ,对SR电机 ,PWM运行方式下的切向力和径向力进行了仿真计算 ,对非能量回馈 (NERVC)和能量回馈 (ERVC)两种不同续流方式下切向力和径向力的大小进行了比较。本文研究对进一步开展SR电机振动抑制策略研究有较大意义。     

水平地震力作用下无铰圆弧拱桥平面挠曲振动方程的闭合解

对无铰圆弧拱桥，在水平地震力作用下，考虑阻尼力的影响时的平面挠曲振动方程进行了推导，并用Ｇａｌｅｒｋｉｎ法得出了一个实用的Ｄｕｈａｍｅｌ积分形式的公式