变速机械振动信号的伪同步重采样技术——I速度与角位置的瞬时估计方法

在机械的变速运行过程中由于在非平稳性，使得大部分等时间间隔采样的传统方法无法适用，利用光电编码器进行角度采样虽可以快速跟踪快速的变化，但其使用安装却受机械装置结构的限制。为解决机械变速过程状态信号的解调和特征提取问题，本文提出了一种新的数据获取和预处理方法－伪同步信号重采样技术，该技术通过对瞬时转速和角位置的估计以及非平稳信号的自适应重采样，获取与转速有关的信息应应用常规的信号处理方法进行特征提以     

变速机械振动信号的伪同步重采样技术——Ⅱ滤波器设计与信号重采样

在变速回转机械信号等转角采样过程中,采样频率随着机械转速的变化而变化,同时,为防止信号频谱混迭,抗频混滤波器的截止频率必须满足采样定理。而对于伪同步信号重采样,由于重采样频率（瞬时转速）和重采样时刻均为连续时变函数,因此,信号的重采样比也应为连续时变函数。本文将探讨重采样滤波器（自适应信号滤波器）的设计问题,并给出信号重采样公式及其数字阶比谱算例。     

声呐信号仿真中一种快速重采样和滤波的方法

首先分析了传统方法在处理速度上的缺陷,然后根据水声信号仿真的特点,提出了一种在频域同时完成重采样和滤波的方法.这种方法的主要过程通过FFT来实现,大大加快了信号仿真的处理速度.试验结果表明,在声呐信号仿真中,该方法能够较快地完成重采样和滤波的任务,使声呐信号的实时仿真得以实现.     

非整周期采样信号相位差估计的相频匹配方法

To improve the precision and anti-interference performance of phase difference estimation for non-integer periods  sampling signals,a phase and frequency matching based phase difference estimation method  was proposed.The phase difference estimation  was obtained by means of the segmented Hilbert transform to suppress the effect of non-integer periods  sampling sinusoidal signals on the Hilbert transform.The simulation results demonstrate that compared with the methods of cross-correlation,Hilbert transform and data extension-based correlation, the proposed method has better phase difference estimation performance for non-integer periods sampling signals in terms of its estimation precision and anti-interference performance.Its phase difference estimation errors are closer to Cramer-Rao lower bound (CRLB).The measurement experiments  on the flow rates of Coriolis mass flowmeter validate the effectiveness of the proposed method.     

CALCULATION OF THE STRESS INTENSITY FACTOR AND ESTIMATION OF ITS ERROR BY A SHAPE SENSITIVITY ANALYSIS

Abstract— The precision with which the stress intensity factor (SIF) can be calculated from a finite element solution depends essentially on the extraction method and on the discretization error. In this paper, the influence of the discretization error in the SIF calculation was studied and a method for estimating the resulting error was developed. The SIF calculation method used is based on a shape design sensitivity analysis; this assures that the resulting error in the extracted SIF depends solely on the global discretization error present in the finite element solution. Moreover, this method allows us to extend the Zienkiewicz-Zhu discretization error estimator to the SIF calculation. The reliability of the proposed method was analysed solving a two-dimensional problem using an h -adaptive process. Also the convergence of the error with the h -adaptive refinement was studied.     

基于振动响应的隔震支座的非线性建模及参数估计

为了研究隔震橡胶支座的力学特性,采用修正的Wen模型分析隔震支座的非线性动力行为,并用试验方法测试得到了该模型的相关参数.鉴于该模型具有高度的非线性,传统的参数识别方法不再适用,本文根据非线性系统状态参数估计理论,利用多项式一阶近似技术来代替EKF滤波技术中的求导线性化过程,估计迟滞模型的非线性参数.该方法具有运算简单、计算精度高、易于实现的优点.通过进行两种简谐激励下的仿真和试验,结果表明隔震支座的模型参数的递推结果相当可靠,从而证实了该方法在隔震支座检测和健康状态评估中的有效性.     

NEW APPROACH FOR ESTIMATION OF ΔJ AND FOR MEASUREMENT OF CRACK GROWTH AT ELEVATED TEMPERATURE

Abstract— The ACPD-method was used to measure crack growth in low cycle fatigue tests at elevated temperature. The material which was investigated at T = 550°C was the ferritic steel 2.25Cr–1Mo. Characteristic values of representative hysteresis loops were determined. The crack growth data were correlated with the effective part of the fracture mechanics parameter Δ J. A new method for the calculation of Δ J is proposed.     

基于两种回归场的SPR误差评估在地震液化数值分析中的比较与应用

在采用有限元方法数值模拟饱和砂土场地地震液化及流动的过程中,由于可液化砂土本构关系的非线性及土与结构接触的复杂性,在动力荷载增量很大时,网格易发生剧烈变形,导致计算结果缺乏需要的精度甚至中止计算。因此,需在计算中进行误差评估,获悉计算精度,为改善网格、优化最终计算结果提供依据。基于详细的SPR误差评估方法的原理和操作流程,比较了两种回归场在典型的液化流动数值案例中的结果和误差分布;结合液化程度、位移矢量分布等讨论了造成误差值大小差异的具体原因,既为数值分析提供可供参考的计算精度,也为进一步优化有限元计算提供合理依据。