【作者】 朱晓冬；

【导师】 王逢瑚；

【作者基本信息】 东北林业大学 ， 木材科学与技术， 2004， 硕士

【摘要】 在小波分析出现之前，信号处理的主要工具是Fourier分析。Fourier分析在处理平稳随机信号方面有着不可替代的作用，而大量的现实存在的信号是非平稳时变的信号，这样Fourier分析显得能力不足。小波分析的出现，是传统信号处理的发展。小波分析是一种有效的处理非稳定信号的方法。它是一种时频分析的有用工具，因而被应用于很多领域。多年的理论和实践表明，小波分析在处理时变信号方面有着得天独厚的优势。 本论文以中密度纤维板为试件，利用弯曲振动试验、纵波共振试验测定其动态弹性模量，分析比较了小波分析和FFT分析的特点和各种试验所得结果之间的关系。 主要结论如下： 1．可以用小波分析的方法测定中密度纤维板的动态杨氏模量。 2．不同方法测得的弹性模量不同，但它们之间存在一定的关系。 3．研究了小波分析在信号消噪方面的实际应用，对试件的振动信号进行了小波消噪，取得了较好的结果。 4．研究了小波分析在非平稳信号分析方面的实际应用，说明了小波分析对此类信号分析有着傅立叶分析不可比拟的优势。通过小波分析处理试件的振动信号，发现中密度纤维板的不同缺陷对其振动信号有不同的影响。 5．小波分析在中密度纤维板缺陷的无损检测具有明显的优越性，小波分析在理论和实践上具有广阔的应用前景。更多还原

【Abstract】 Before the advent of Wavelet Analysis, the chief tool on signal processing is Fourier analysis. Fourier analysis is an irreplaceable tool on processing stationary stochastic signals, but is at a loss on processing non-stationary time-varying signals that abound in real world. Thus wavelet analysis was introduced. It is development of methods on signal processing. Wavelet analysis is an effective method for processing an unsteady signal. It is a useful tool for time-frequency analysis, and is therefore applied in various fields. During many years theoretical and applied study, it is superior to other tools on processing time-varying signals.The samples used in this study were medium density fiberboard (MDF). Their dynamic modulus of elasticity was measured by flexural vibration and longitudinal resonant vibration .A comparison is made between FFT Analysis and wavelet Analysis.The main results are as follows:1) We can measure the dynamic elasticity modulus of MDF by Wavelet Analysis.2) The modulus of elasticity that measured by different tests was different. But there was a correlation between them.3) The research on the application of wavelet transform in signal noise reduction is conducted. The approach of noise reduction based on wavelet denoise is proposed. The results of experiments with vibration signal of the samples show that the approach can be applied to noise reduction effectively.4) The research on the application of wavelet transform in non-stationary signal is conducted. It is made out that wavelet analysis in these signals has a great advantage over Fourier analysis. Through processing vibration signal of the samples, it can be seen that the different defects of MDF have the different influences to the vibration character of the samples.5) It can be acquired that wavelet analysis has the advantages in collecting the defect characters of the MDF. In conclusion, wavelet analysis is worthwhile doing both in theory and practices.更多还原