太赫兹无损检测中缺陷探测的方法研究

发布时间：2018-05-16 15:39

本文选题：太赫兹无损检测 + 小波变换　；参考：《华中科技大学》2015年硕士论文

【摘要】：本论文主要提出并检验了一种通过太赫兹波来分析样品内部缺陷的方法。这种方法能够通过工程数学来处理样品的太赫兹波三维扫描数据,然后得到样品的内部缺陷情况,如样品内缺陷的大小和分布,并具有广泛的适用范围。全文从理论研究、实验设计和实验结果分析三个方面对这种方法进行了描述。其中,小波变换理论和利普希茨连续条件理论是这种方法的理论基础。小波变换的时频分析手段非常适合于提取这种由缺陷造成的小范围突变信号,同时,由利普希茨连续条件产生的指数工具能很好的描述突变信号的变化快慢和程度。因此,在小波变换的基础上利用利普希茨指数衡量样品的内部缺陷情况能获得很好的效果。为了对缺陷状况进行最直观的描述,本论文根据利普希茨指数的统计规律设计了一个权值,用来衡量样品内的某一区域是缺陷的可能性。本论文设计了一系列实验来验证这种方法的有效性,并严谨的进行了样件准备、仪器选择以及算法设计等过程,实验中的一些比较重要的参数都是通过进行多次对比实验的方式而决定的。整个实验过程是在尽量模拟实际状况的原则下进行的,力求实验结果具有代表性。在进行了简单的处理之后,本论文对实验结果进行了全面分析。实验结果表明,这种方法能从一定程度上反映出样品内部的缺陷情况,并具有较大的可靠程度,同时还能自由的调节判断标准的严格程度。
[Abstract]:In this paper, we propose and test a method to analyze the internal defects of samples by terahertz wave. This method can process the terahertz wave 3D scanning data of samples by engineering mathematics, and then obtain the internal defects of the samples, such as the size and distribution of the defects in the samples, and have a wide range of application. This method is described from three aspects: theoretical research, experimental design and analysis of experimental results. Wavelet transform theory and Lipschitz continuous condition theory are the theoretical basis of this method. The time-frequency analysis method based on wavelet transform is very suitable for extracting the small range abrupt signal caused by the defect. At the same time, the exponential tool produced by Lipschitz continuity condition can describe the change speed and degree of the abrupt change signal very well. Therefore, on the basis of wavelet transform, using Lipschitz index to measure the internal defects of samples can obtain good results. In order to describe the defect state intuitively, this paper designs a weight value according to the statistical law of Lipschitz index, which is used to measure the possibility that a certain region in the sample is a defect. In this paper, a series of experiments are designed to verify the effectiveness of this method, and the process of sample preparation, instrument selection and algorithm design are carefully carried out. Some of the more important parameters in the experiment are determined by several comparative experiments. The whole experiment process is carried out under the principle of simulating the actual situation as far as possible, and the experimental results are representative. After a simple treatment, the experimental results are analyzed comprehensively in this paper. The experimental results show that this method can reflect the defects in the sample to a certain extent and has a greater degree of reliability. At the same time, it can freely adjust the strict degree of the judgment standard.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O441.4

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