INFRARED PHYSICS & TECHNOLOGY
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2022
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IF 2.997
Ying Xu,Xuelei Jiang
The corrosion of steel plates is one of the main reasons for the decrease of bearing capacity and structural durability. The existing nondestructive testing (NDT) approaches is difficult to accurately detect steel plate corrosion, including the location and degree of corrosion. Therefore, a non-contact nondestructive terahertz time-domain spectroscopy (THz-TDS) is utilized to evaluate the corrosion based on the properties of THz waves. The experimental results show that in the effective frequency range of 0.2–1.2 THz, the refractive index of corrosion products is around 2.8, and Fe 3 O 4 has a significant impact on the optical parameters of the corrosion products mixture. The relative amplitude of the first signal from reflection THz-TDS exhibits a logarithmic relationship with the corrosion time of the steel plates and a linear relationship with the reciprocal of the corrosion time. By the method of extracting the delay time difference in the reflected THz signal, the THz-TDS can accurately measure the corrosion layer with a thickness larger than 40 μm, and the measurement accuracy is over 90 %. Meanwhile, the 3-dimensional (3D) visualization based on the THz method directly describes the true thickness and geographical distribution of the corrosion layer while removing the influence of coating materials. It provides a novel way to quantify corrosion degree of steel plate through NDT of corrosion under coating and extraction of corrosion thickness. The applicability and accuracy of non-contact THz-TDS for corrosion detection are therefore proved.
研究领域:
材料科学
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无损检测技术
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光学工程
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产品关联
DOI
高影响因子
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
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2025
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IF 5.9
Lirong Gong,Yan Qiu,Haobo Zhai,Ruifan Dan,Yuan Dang,Weihua Liu,Long Hu,Yuhua Hang,Yongdong Li
Ethylene-Vinyl Acctate-copolymers (EVAs) are widely used in the manufacture of wires and cables as electrical insulating media in electric power fields. Oxidation is one of the primary mechanisms leading to the aging of polymer materials, and the addition of antioxidants can effectively slow the oxidation reaction. Current nondestructive testing methodologies face challenges in the measurement of antioxidant concentrations, which constitute a critical metric for aging assessments. In this article, we propose a method for measuring antioxidant concentration using terahertz time-domain spectroscopy (THz-TDS). In comparison to other techniques such as liquid chromatography, no elaborate sample preparation is necessary, and calibration measurements can be conducted rapidly. The spectral changes caused by the addition of different concentrations of antioxidants were investigated, and the results showed that the refractive index and dielectric constant increased significantly with a decrease in the antioxidant concentration. When the concentration of antioxidant 1010 in the sample was increased from 0% to 10%, the refractive index decreased from 1.55 to 1.42, and the dielectric constant decreased from 2.38 to 2.03 average over the band of 0.5–2.5 THz. Moreover, the numerical calculation using density functional theory (DFT) showed the introduction of oxygen-containing functional groups of antioxidant 1010 molecules into EVA molecules slightly reduced the polarization, resulting in a consistently decrease in the dielectric constant of the constructed materials compared with original EVA materials. The classification of antioxidant concentration in EVA was predicted using machine learning, including partial least squares regression (PLSR), random forest (RF), support vector regression (SVR), and extreme gradient boosting (XGboost). XGboost was found to have the highest prediction accuracy with an root mean square error (RMSE) of 0.0412. In order to ascertain the characteristic spectrum of the 1010 antioxidant, we selected the dielectric constant at the 0.9 THz position for a linear fit. The RMSE of cross-validation (RMSECV) value for leave-one-out cross validation (LOOCV) was found to be 0.38.
研究领域:
高分子材料科学
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电力绝缘材料
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非破坏性检测
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光谱分析
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材料老化评估
✓ 已验证
产品关联
DOI
高影响因子
Journal of Spectroscopy
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2022
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IF 1.75
Shubao Pan,Huo Zhang,Zhi Li,Tao Chen,Xianhua Yin
This paper introduces a method to detect the content of sucrose, an adulterant of red ginseng, based on terahertz spectroscopy. Experiments were carried out on red ginseng with 6 levels of adulterated concentrations using terahertz time-domain spectroscopy (THz-TDS). We separately extracted the information of the terahertz spectral curve by principal component analysis (PCA) and Monte Carlo uninformative variable elimination (MCUVE) and then separately performed quantitative analysis by partial least squares regression (PLSR) and support vector regression (SVR). Because the nonlinear line factor in the terahertz spectral curve of red ginseng samples is considered, the MCUVE-SVR has high correlation coefficient (>0.99) and ratio prediction to deviation (>7.4), low root means square error of deviation (<1.2%), and Bias (<0.05%). The results prove that MCUVE-SVR can be regarded as an ideal quantitative analysis method in the detection of sucrose incorporation in red ginseng by terahertz spectroscopy.
研究领域:
中药学
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光谱分析
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食品检测
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产品关联
DOI
高影响因子
MICROCHEMICAL JOURNAL
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2025
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IF 5.1
Leijun Xu,Xiaoyan Geng,Jihong Deng,Zhenshuo Chen,Dengmin Li,Hui Xiao,Hui Jiang
The safety of wheat flour as a crucial food ingredient is paramount. Benzoyl peroxide (BPO) is banned in wheat flour in many regions due to health risks, yet it may be illegally added to enhance appearance. In the present study, BPO adulteration in wheat flour was quantitatively analyzed using terahertz time-domain spectroscopy (THz-TDS). First, the spectral characterization of wheat samples at 0.1–6 THz was obtained, and THz spectral data within specific frequency bands was processed using Savitzky-Golay (SG) filtering. Then, Competitive Adaptive Reweighted Sampling (CARS) and Variable Combination Population Analysis (VCPA) methods were used to select optimal frequency points. Finally, a chemometric model combining linear models (Lasso Regression, Ridge Regression, and Partial Least Squares Regression) with nonlinear models (Back-Propagation Neural Network, Random Forest, and Support Vector Machine) was employed for quantitative analysis. The experimental outcomes demonstrated that the detection models established through the standard analytical process met the detection requirements ( R P ≥ 0.95), and the best performance results were obtained from the chemometric models based on linear relationships. Among them, the Lasso Regression and Ridge Regression models obtained after optimization of the VCPA method had high prediction accuracy ( R P ≥ 0.97). The results showed that the THz spectroscopy technique combined with standard chemical analysis procedure could effectively realize the quantitative detection of BPO in wheat flour, providing an efficient and reliable tool for the safety detection of wheat flour.
研究领域:
食品安全
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光谱学
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分析化学
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化学计量学
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应用物理学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）