本文選題：太赫茲無損檢測 + 小波變換�。� 參考：《華中科技大學》2015年碩士論文

【摘要】：本論文主要提出并檢驗了一種通過太赫茲波來分析樣品內部缺陷的方法。這種方法能夠通過工程數學來處理樣品的太赫茲波三維掃描數據,然后得到樣品的內部缺陷情況,如樣品內缺陷的大小和分布,并具有廣泛的適用范圍。全文從理論研究、實驗設計和實驗結果分析三個方面對這種方法進行了描述。其中,小波變換理論和利普希茨連續(xù)條件理論是這種方法的理論基礎。小波變換的時頻分析手段非常適合于提取這種由缺陷造成的小范圍突變信號,同時,由利普希茨連續(xù)條件產生的指數工具能很好的描述突變信號的變化快慢和程度。因此,在小波變換的基礎上利用利普希茨指數衡量樣品的內部缺陷情況能獲得很好的效果。為了對缺陷狀況進行最直觀的描述,本論文根據利普希茨指數的統(tǒng)計規(guī)律設計了一個權值,用來衡量樣品內的某一區(qū)域是缺陷的可能性。本論文設計了一系列實驗來驗證這種方法的有效性,并嚴謹的進行了樣件準備、儀器選擇以及算法設計等過程,實驗中的一些比較重要的參數都是通過進行多次對比實驗的方式而決定的。整個實驗過程是在盡量模擬實際狀況的原則下進行的,力求實驗結果具有代表性。在進行了簡單的處理之后,本論文對實驗結果進行了全面分析。實驗結果表明,這種方法能從一定程度上反映出樣品內部的缺陷情況,并具有較大的可靠程度,同時還能自由的調節(jié)判斷標準的嚴格程度。
[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.
【學位授予單位】：華中科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：O441.4

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