本文選題：超聲　切入點(diǎn)：S變換　出處：《振動(dòng)與沖擊》2017年22期

【摘要】：缺陷回波的檢測是超聲探傷的一項(xiàng)重要內(nèi)容,為減弱噪聲的影響準(zhǔn)確檢測缺陷回波,提出基于S變換時(shí)頻分析和時(shí)頻譜空間濾波的信號(hào)處理方法。討論了高斯回波模型下的到達(dá)時(shí)間和中心頻率與S變換時(shí)頻譜的關(guān)系,說明了利用S變換時(shí)頻譜幅值矩陣的極值提取回波到達(dá)時(shí)間和中心頻率的合理性;為檢測回波,首先對(duì)原始信號(hào)作S變換,然后對(duì)得到的時(shí)頻譜幅值矩陣應(yīng)用最大熵法自適應(yīng)選擇去噪閾值,對(duì)S變換時(shí)頻譜作空間濾波完成降噪;從降噪后的區(qū)域中提取反映缺陷的到達(dá)時(shí)間和中心頻率;對(duì)降噪后的時(shí)頻譜作S逆變換,獲得缺陷回波明顯的時(shí)域信號(hào)。仿真研究表明,基于S變換和時(shí)頻譜空間濾波的方法能夠有效去除噪聲,檢測回波。棒材試塊的實(shí)驗(yàn)結(jié)果同樣表明了該方法在缺陷檢測上的有效性。
[Abstract]:The detection of defect echo is an important part of ultrasonic flaw detection. This paper presents a signal processing method based on S-transform time-frequency analysis and time-spectrum spatial filtering, and discusses the relationship between the time of arrival and center frequency under Gao Si's echo model and the S-transform time-frequency spectrum. The rationality of extracting the arrival time and center frequency of echo by using the extreme value of spectrum amplitude matrix in S transform is explained. In order to detect the echo, the original signal is first transformed by S transform. Then the maximum entropy method is used to select the denoising threshold of the time-spectrum amplitude matrix, and the S-transform spectrum is filtered by spatial filtering, and the time of arrival and the center frequency of the defect are extracted from the de-noised region. The time-domain signal with obvious defect echo is obtained by S-inversion of the time spectrum after noise reduction. The simulation results show that the method based on S-transform and time-spectrum spatial filtering can effectively remove the noise. The experimental results of echo and bar test also show that the method is effective in defect detection.
【作者單位】： 浙江大學(xué)流體動(dòng)力與機(jī)電系統(tǒng)國家重點(diǎn)實(shí)驗(yàn)室;北京航天發(fā)射技術(shù)研究所;
【基金】：浙江省自然科學(xué)基金(LY14E050013) 浙江省公益技術(shù)研究工業(yè)項(xiàng)目(2015C31052) 重慶齒輪箱有限責(zé)任公司"海面平臺(tái)洋流發(fā)電裝備研制與開發(fā)"
【分類號(hào)】：TB553

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1 陳生;唐能福;;動(dòng)態(tài)空間濾波的探討與實(shí)踐[J];廣西師范學(xué)院學(xué)報(bào)(自然科學(xué)版);2006年01期

2 鄭剛，孫逸平;用照相及濾波技術(shù)實(shí)現(xiàn)圖象相減[J];上海機(jī)械學(xué)院學(xué)報(bào);1994年03期

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