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Semi-supervised libs quantitative analysis method based on co-training regression model with selection of effective unlabeled samples

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Plasma Science and Technology 2019年第3期21卷 114-124页

作者：李晓萌陆慧丽阳建宏常福 School of Mechanical Engineering University of Science and Technology Beijing Basic Experimental Center of Natural Science University of Science and Technology Beijing

The accuracy of laser-induced breakdown spectroscopy(libs) quantitative method is greatly dependent on the amount of certified standard samples used for training. However, in practical applications, only limited standard samples with labeled certified concentrations are available. A novel semi-supervised libs quantitative analysis method is proposed, based on co-training regression model with selection of effective unlabeled samples. The main idea of the proposed method is to obtain better regression performance by adding effective unlabeled samples in semisupervised learning. First, effective unlabeled samples are selected according to the testing samples by Euclidean metric. Two original regression models based on least squares support vector machine with different parameters are trained by the labeled samples separately, and then the effective unlabeled samples predicted by the two models are used to enlarge the training dataset based on labeling confidence estimation. The final predictions of the proposed method on the testing samples will be determined by weighted combinations of the predictions of two updated regression models. Chromium concentration analysis experiments of 23 certified standard high-alloy steel samples were carried out, in which 5 samples with labeled concentrations and 11 unlabeled samples were used to train the regression models and the remaining 7 samples were used for testing. With the numbers of effective unlabeled samples increasing, the root mean square error of the proposed method went down from 1.80% to 0.84% and the relative prediction error was reduced from 9.15% to 4.04%.

关键词： libs effective unlabeled samples co-training semi-supervised labeling confidence estimation

A method of laser focusing control in microlaser-induced breakdown spectroscopy

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Plasma Science and Technology 2019年第3期21卷 31-39页

作者：汪为孙兰香张鹏郑黎明齐立峰董伟 Shenyang Institute of Automation Chinese Academy of Sciences Institutes for Robotics and Intelligent Manufacturing Chinese Academy of Sciences University of Chinese Academy of Sciences Key Laboratory of Networked Control System Chinese Academy of Sciences

This paper presents a method for the automatic adjustment of the laser defocusing amount in micro-laser-induced breakdown spectroscopy. A microscopic optical imaging system consisting of a CCD camera and a 20× objective lens was adopted to realize the method. The real-time auto-focusing of the system was achieved by detecting the effective pixels of the light spot generated by the laser pointer. The focusing accuracy of the method could achieve 3 μm. The element concentrations of Mn and Ni in low-alloy steels were analyzed at a crater diameter of about 35 μm using the presented method. After using the presented method, the determination coefficients of Mn and Ni both exceeded 0.997, with the root-mean-square errors being 0.0133 and 0.0395, respectively. Scanning analysis was performed on the inclined plane and the curved surface by means of focusing control and non-focusing control. Ten characteristic spectral lines of Fe were selected as the analysis lines. With the focusing control, the average relative standard deviations obtained on the inclined plane and curved surface were both less than 5%, and much less than the values without focusing control, 14.6% and 40.39%.

关键词： libs microanalysis ablation crater focusing control

Uranium measurements using laser-induced breakdown spectroscopy in lithium chloride-potassium chloride salt of pyroprocessing

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Plasma Science and Technology 2020年第7期22卷 110-115页

作者： Seul-Ki HAN Se-Hwan PARK Seong-Kyu AHN Korea Atomic Energy Research Institute Yuseong-guDaejeon 34057Republic of Korea

In pyroprocessing,uranium(U) is recovered from molten LiCl-KCl salt,and,for safeguard purposes,it is important to analyze the U and Plutonium(Pu) concentrations in a timely manner.In the present work,salt samples containing U were fabricated.The laser used in the present work was an Nd:YAG laser with a wavelength of 532 nm,a laser energy on the sample of11.5 mJ,and a pulse repetition rate of 10 Hz.The plasma emission light was measured with an Echelle spectrometer.A total of 100 points on the sample surface were measured as the laser incident position was changed.The U and potassium(K) peaks in the spectrum were identified.Univariate and multivariate analyzes were conducted to determine the accuracy and limit of detection(LOD) of the laser-induced breakdown spectroscopy.

关键词： libs uranium(U) safeguards LOD

激光诱导击穿等离子体发射光谱技术测定土壤中铅的研究

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现代科学仪器 2022年第2期39卷 29-32页

作者：沈明富俞耀坪浙江杭康检测技术有限公司浙江杭州310015

由于在土壤中包含较多的元素,这些元素谱线不同,造成谱线有吸附性和自蚀现象,导致检测结果准确性较差,为此利用激光诱导击穿等离子体发射光谱(libs)测定土壤中铅的含量。分析libs技术检测原理并设置实验装置,采集与预处理待检测土壤,计... 详细信息

由于在土壤中包含较多的元素,这些元素谱线不同,造成谱线有吸附性和自蚀现象,导致检测结果准确性较差,为此利用激光诱导击穿等离子体发射光谱(libs)测定土壤中铅的含量。分析libs技术检测原理并设置实验装置,采集与预处理待检测土壤,计算样品等离子体的温度与密度值后,获取土壤样品的组分和含量信息,最后采用最小二乘法实现土壤重金属含铅量的检测。实验结果表明,所提方法土壤重金属含铅量检测值与实际情况相差较小,提高了检测准确性和实时性,可以满足检测方法的设计需求。

关键词： libs 土壤重金属含铅量最小二乘法密度值

Quantitative analysis of the content of nitrogen and sulfur in coal based on laserinduced breakdown spectroscopy: effects of variable selection

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Plasma Science and Technology 2020年第7期22卷 36-43页

作者：邓凡丁宇陈雨娟朱绍农陈非凡 Jiangsu Key Laboratory of Big Data Analysis Technology Nanjing University of Information Science&TechnologyNanjing 210044People's Republic of China Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology Nanjing University of Information Science&TechnologyNanjing 210044People's Republic of China Jiangsu Engineering Research Center on Meteorological Energy Using and Control Nanjing University of Information Science&TechnologyNanjing 210044People's Republic of China

Coal is a crucial fossil energy in today’s society,and the detection of sulfir(S) and nitrogen(N)in coal is essential for the evaluation of coal quality.Therefore,an efficient method is needed to quantitatively analyze N and S content in coal,to achieve the purpose of clean utilization of coal.This study applied laser-induced breakdown spectroscopy(libs) to test coal quality,and combined two variable selection algorithms,competitive adaptive reweighted sampling(CARS) and the successive projections algorithm(SPA),to establish the corresponding partial least square(PLS) model.The results of the experiment were as follows.The PLS modeled with the full spectrum of 27,620 variables has poor accuracy,the coefficient of determination of the test set(R^2 P) and root mean square error of the test set(RMSEP) of nitrogen were 0.5172 and 0.2263,respectively,and those of sulfur were0.5784 and 0.5811,respectively.The CARS-PLS screened 37 and 25 variables respectively in the detection of N and S elements,but the prediction ability of the model did not improve significantly.SPA-PLS finally screened 14 and 11 variables respectively through successive projections,and obtained the best prediction effect among the three methods.The R^2 P and RMSEP of nitrogen were0.9873 and 0.0208,respectively,and those of sulfur were 0.9451 and 0.2082,respectively.In general,the predictive results of the two elements increased by about 90% for RMSEP and 60% for R2 P compared with PLS.The results show that libs combined with SPA-PLS has good potential for detecting N and S content in coal,and is a very promising technology for industrial application.

关键词： variable selection libs coal CARS and SPA

Calibration curve and support vector regression methods applied for quantification of cement raw meal using laser-induced breakdown spectroscopy

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Plasma Science and Technology 2019年第3期21卷 23-30页

作者：贾军伟付洪波侯宗余王华东倪志波董凤忠 Anhui Provincial Key Laboratory of Photonic Devices and Materials Anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences University of Science and Technology of China State Key Lab of Power Systems Department of Thermal Engineering Tsinghua-BP Clean Energy Center Tsinghua University

Laser-induced breakdown spectroscopy(libs) is a qualitative and quantitative analytical technique with great potential in the cement industrial analysis. Calibration curve(CC) and support vector regression(SVR) methods coupled with libs technology were applied for the quantification of three types of cement raw meal samples to compare their analytical concentration range and the ability to reduce matrix effects, respectively. To reduce the effects of fluctuations of the pulse-to-pulse, the unstable ablation and improve the reproducibility, all of the analysis line intensities were normalized on a per-detector basis. The prediction results of the elements of interest in the three types of samples, Ca, Si, Fe, Al, Mg, Na, K and Ti, were compared with the results of the wet chemical analysis. The average relative error(ARE),relative standard deviation(RSD) and root mean squared error of prediction(RMSEP) were employed to investigate and evaluate the prediction accuracy and stability of the two prediction methods. The maximum average ARE of the CC and SVR methods is 34.62% instead of 6.13%,RSD is 40.89% instead of 7.60% and RMSEP is 1.34% instead of 0.43%. The results show that SVR method can accurately analyze samples within a wider concentration range and reduce the matrix effects, and libs coupled with it for a rapid, stable and accurate quantification of different types of cement raw meal samples is promising.

关键词： cement raw meal calibration curves SVR libs

Remote open-path laser-induced breakdown spectroscopy for the analysis of manganese in steel samples at high temperature

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Plasma Science and Technology 2019年第3期21卷 52-59页

作者：崔敏超出口祥啓王珍珍田中诚也全敏奎藤田裕贵赵升吨 School of Mechanical Engineering Xi'an Jiaotong University Graduate School of Advanced Technology and Science University of Tokushima State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Division of Mechanical Engineering Korea Maritime and Ocean University School of Mechanical Engineering Xi’an Jiaotong University

A remote open-path laser-induced breakdown spectroscopy(libs) system was designed and studied in the present work for the purpose of combining the libs technique with the steel production line. In this system, the relatively simple configuration and optics were employed to measure the steel samples at a remote distance and a hot sample temperature. The system has obtained a robustness for the deviation of the sample position because of the open-path and alloptical structure. The measurement was carried out at different sample temperatures by placing the samples in a muffle furnace with a window in the front door. The results show that the intensity of the spectral lines increased as the sample temperature increased. The influence of the sample temperature on the quantitative analysis of manganese in the steel samples was investigated by measuring ten standard steel samples at different temperatures. Three samples were selected as the test sample for the simulation measurement. The results show that, at the sample temperature of 500 ℃, the average relative error of prediction is 3.1% and the average relative standard deviation is 7.7%, respectively.

关键词： remote open-path libs steel manganese sample temperature quantitative analysis

Identification of Cu in <i>Crassostrea virginica</i>Tissue Using the Technique of Laser-Induced Breakdown Spectroscopy (libs)

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Optics and Photonics Journal 2021年第3期11卷 51-62页

作者： Xochitl Patricia Urrutia-Meza Fabio Felipe Chalé-Lara Rogelio Ortega-Izaguirre Instituto Politécnico Nacional Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada U. Altamira Altamira México

The analysis of metals in aquatic organisms is of great importance due to the health problems they can cause to be consumed by human beings. In this study, the Laser-Induced Plasma Spectroscopy (libs) technique is evaluated as an alternative method to identify Cu in Crassostrea virginica oysters’ tissue. It focuses on the characterization of oysters caught a natural bank and the identification of different Cu concentrations. To carry out experimentation, oyster samples were collected in autumn (October 2017) and spring (May 2018) from San Andres Lagoon, Aldama, Tamaulipas. A single pulse Nd:YAG laser (1064 nm) was used, and tissue was contaminated with 0, 2, 10, 20, 50, and 100 μg/g of Cu. In tissue were identified atomic lines for Ca, Cr, Mg, Mn, Na, N, O, and H. However, the intensities of emission lines for autumn samples were greater than spring samples. Cu emission lines at 324.6, 327.1, 510.3, 515.1, and 521.5 nm were found for contaminated pills. The intensity of emission lines showed a linear increase with the concentration;whereby, they can be used as calibration curves to quantify Cu concentrations in oyster tissue.

关键词： libs Crassostrea virginica Heavy Metals

Development of a Simple Software Program Used for Evaluation of Plasma Electron Density in libs Experiments via Spectral Line Shape Analysis

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Journal of Signal and Information Processing 2012年第4期3卷 502-515页

作者： Ashraf Mohmoud El Sherbini Abdel Aziz Saad Al Aamer Department of Physics Collage of ScienceAl Imam Muhammad Ibn Saud Islamic University(AMISU)Al RiyadhKSA Laboratory of Lasers and New Materials Department of PhysicsFaculty of ScienceCairo UniversityGizaEgypt

A Software program has been developed in order to perform a fast and reliable calculation to plasma electron density in laser induced breakdown spectroscopy (libs) experiments. This program is based on analyzing the emitted spectral line shape via utilizing facilities of the MatLab7? package to perform this task. This software can perform the following tasks;read the exported data file (*txt-format) from ICCD camera-software, specify the working wavelength of interest, removes the continuum emission component appeared under the line, calculates the spectral line intensity of the line, calculates the spectral shift of the line from the tabulated values, correct against spectral shift jitter at the peak emission, de-convoluting and extracting the different components contributing to the emitted line full width at half of the maximum (FWHM) and finally calculates the plasma electron density. In this article we shall present the results of the test measurement of the plasma electron density utilizing spectral line shape analysis to the emitted Hα-line, Si I-line at 288.15 nm and O I-line at 777.2 nm at different camera delay times ranging from 1 to 5 μs.

关键词： Software libs Hα-Line Electron Density MatLab7