基于嵌入式系统的电机振动分析仪设计

本文介绍了一种利用触控式面板模块工具在WindowsCE系统上开发LabVIEW程序的方法,并将该方法运用到对电机振动测量与分析上,构成了以嵌入式系统为平台的便携式电机振动分析设备。应用LabVIEW软件的强大数学运算功能对振动信号作频谱分析,作为电机故障的预防和诊断依据,具有重要的意义。     

Suppressing intersample behavior in iterative learning control

Iterative Learning Control (ILC) is a control strategy to improve the performance of digital batch repetitive processes. Due to its digital implementation, discrete time ILC approaches do not guarantee good intersample behavior. In fact, common discrete time ILC approaches may deteriorate the intersample behavior, thereby reducing the performance of the sampled-data system. In this paper, a generally applicable multirate ILC approach is presented that enables to balance the at-sample performance and the intersample behavior. Furthermore, key theoretical issues regarding multirate systems are addressed, including the time-varying nature of the multirate ILC setup. The proposed multirate ILC approach is shown to outperform discrete time ILC in realistic simulation examples.     

Parameter identification of periodical signals: Application to measurement and analysis of ocean wave forces

This article presents an approach based on state observers to identify the parameters of an unknown periodic force exerted on a mechanical system. This approach comprises two stages and can be executed in real time by using only displacement measurements. The first stage goal is the estimation of the coefficients of a Fourier series that approximates the periodic force. From the estimated coefficients, the phase and the amplitude of the signal can be simultaneously computed; and from the estimated force, in a second stage, the frequencies of the signal can be estimated. To perform the tasks at each stage, two state observers were designed. To show the applicability of the proposed approach, the reconstruction of a wave force affecting a marine structure as well as the computation of the amplitude and phase of its spectral components was taken as case of study. The performance of the state observer was examined by means of simulations and off-line tests carried out with experimental data. Such data were obtained by executing laboratory tests and measuring waves in the Caribbean sea.     

分布式光纤振动传感系统的多级零频点定位研究

为了减少直线结构Sagnac分布式光纤传感系统的定位误差,提出一种多级零频点的优化方法,通过分析直线结构Sagnac分布式光纤传感定位原理,确定固定的采样速率下离散化是造成定位误差大的原因.并分析得出振动信号频域曲线会周期出现多个零频点,进而对振动定位的多级零频点优化方法进行了理论推导,阐明高倍零频点下的定位误差会有效减小.通过实验验证表明,在总长为11.769 km的传感光纤上,优化后的定位方法在不改变采样速率下可保证定位误差提升到±20 m范围内,可以基本满足系统对外界振动信号进行精确定位的要求.     

抑制噪声的问题探索

本论文是探讨脉冲探测技术的,探讨了两个问题：要求实现信噪比的改善,最后形成高灵敏度的探测系统;在白噪声中探测宽度为τ的脉冲信号问题。     

《建筑工程容许振动标准》简介

根据国家标准《建筑工程容许振动标准》编制的原则,阐述了标准编制的目的、简要过程和主要内容.     

受控振动柱体对波浪影响的数值模拟研究

以不可压缩黏性流体的Navier-Stokes方程为控制方程,采用RNG k-ε湍流模型,利用VOF方法追踪运动的自由表面的方法,建立了三维数值波浪与振动柱体相互作用的模型.基于经典绕射理论验证了波浪绕固定柱体传播的数值模型的可靠性,再采用动边界技术赋予柱体振动规律,研究受控振动柱体对波浪传播的影响,并通过控制柱体初始振动相位变化,系统地给出了在柱体振动的不同初始相位下柱体前后波浪变化的规律.     

低速旋转机器振动测试与评价

低转速机器振动频率低、幅值小,测量困难.在考察转子的平衡情况时,不能仅通过振动幅值的大小来评价转子的平衡状况,而应该通过试加重量计算加重灵敏度以后,再计算出转子残余不平衡量并与标准要求值进行比较和判断.     

有限差分法计算HF分子的振动能级和光谱

本文用有限差分法计算了HF分子的振动能级并且把计算的结果用切比雪夫法进行拟合得到了HF的光谱项,将所得结果与黄整等人的用时域有限差分法计算所的结果和实验值进行了比较。     

桥梁风工程研究的若干新进展

介绍我们近年来结合桥梁抗风实际需要的4项研究成果。(1)桥梁节段模型强迫振动风洞实验方法与相应的颤振导数时域识别法与频域识别法,用同一批实验数据作了两种方法的对比研究。频域法自身包含有滤波过程,因而抗干扰能力强,识别的颤振导数曲线平顺光滑;时域法的定解方程对信号相位差较敏感,易受杂波干扰导致结果漂移或波动。(2)以佛山平胜大桥为工程背景,研究了上下行车道主梁相互独立并行带来的双幅桥面的气动干扰及串列双主缆的气动干扰问题。(3)拉索风雨振现场观测与振动控制研究。在岳阳洞庭湖大桥建立了风雨振观测系统,并连续四年进行了长时间现场观测,在风速、风向、雨量等参数对风雨振的影响规律与拉索风雨振振动形态方面有新的发现。开发了一套磁流变式拉索减振新技术,并已于2002年在岳阳洞庭湖大桥全桥实施,三年来显示了良好的减振效果。(4)针对城市桥梁磁流变减振系统的低压供电线路最易受到人为的破坏的问题,设计开发了一种永磁调节装配式磁流变阻尼器(PMAA-MR),并将其成功应用于长沙洪山大桥的拉索减振。