基于延时嵌入法的往复式压缩机关联维数提取技术

论述了利用嵌入相空间重构方法确定往复式压缩机振动信号关联维数的技术。将自相关函数法和伪相图法结合起来,能够更加直观、合理地选择时间延迟。在对振动信号重构的基础上,给出了标度的取值范围。将此技术应用于往复式压缩机故障诊断中,验证了该技术的准确性和有效性。

基于延时嵌入法的大机组故障特征提取技术

论述了延时嵌入相空间重构方法及其伪相图的获取技术 ,将这一方法用于大机组非线性故障的定性特征提取。几个故障实例的分析结果表明 :伪相图在一定程度上与转子的轴心轨迹类似。由于伪相图可通过一维时间序列而得到 ,而且伪相图的构造过程包含了降噪过程。因此 ,将伪相图应用于大机组非线性故障的特征提取具有一定的优越性。

基于相空间重构技术的国际原油价格时序特征

由于国际原油市场的复杂性,结构性预测方法很难实现准确的国际原油价格预测。因此,通过原油价格的时间序列,分析原油市场随时间变化的历史行为和规律,建立时间序列预测模型成为原油价格预测的又一重要研究方向。在建立原油价格时间序列预测模型之前,必须掌握原油价格时间序列的特征,才能选择合适的原油价格时间序列预测方法。

Nonlinear characteristics and functional analysis of masseter electromyography

The C-C method was adopted to analyze the nonlinear characteristics of masseter electromyography （EMG） signals and the chaotic degree by the largest Lyapunov exponent （LLE） of different genders and sides. First, the embedding dimension and the delay time were obtained through this method, then the phase space was reconstructed to resume the chaotie attractor and determine the LLE. The result shows that the trajectory of attractor is denser than Chen＇s attractor, and the LLE is positive, which means that not only the signal has the character of chaos, but also the chaotic degree of masseter EMG is relatively high. According to the value of the LLE, the chaotic degree of men＇s masseter EMG is higher than that of women＇s; when the dentition is normal, the chaotic degree of two sides is almost the same. Then, a conclusion can be deduced that if the LLE of both sides are in great difference, the unilateral mastication is likely to exist, which means that the nonlinear characteristics of masseter EMG can be applied to predict the unilateral mastication.