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1.
虚拟仿真实验作为大型仪器分析实验教学模式的新兴趋势,有效地将虚拟仿真技术与实物仪器教学相结合,最大限度地提升了学生对于大型仪器分析的综合应用能力.本文以激光诱导击穿光谱(LIBS)虚拟仿真实验系统为例,完整地模拟了LIBS系统的样品处理、光谱采集、定性分析和定量分析等实际实验场景,通过虚实结合实验教学模式对实验过程进行实时跟踪与综合考评.该实验有助于提高学生自主探究能力和创新意识,培养具有独立思考与实践能力的拔尖人才.  相似文献   

2.
我国当前主要能源仍是煤炭资源,煤质快速检测有利于其清洁高效利用。激光诱导击穿光谱(Laser-Induced Breakdown Spectroscopy,LIBS)作为一种快速光谱检测技术,具有样品需求量小、制样简便、可多元素同时测量等优点,其在煤质快速检测中的应用潜力已得到广泛认可。本文从激光诱导击穿光谱仪器(实验室台式、在线式和便携式)的研发现状、激光诱导击穿光谱对煤质(金属元素、非金属元素和工业指标)的检测现状、煤质分析性能提升方法,以及激光诱导击穿光谱定量分析模型研究等方面介绍了近几年来LIBS技术在煤质检测中的应用现状及未来展望。  相似文献   

3.
炉内结渣是影响火电机组和气化工艺可靠运行的关键因素之一,准确预测灰熔点可以提前调整炉膛出口温度以避免结渣。本论文采用激光诱导击穿光谱(LIBS)采集煤灰样中金属元素的光谱,分别建立煤灰中的金属元素的谱线强度与煤灰熔点的随机森林模型、支持向量机回归模型和线性回归模型,直接预测煤灰熔点温度。采用基于马氏距离(MD)的异常数据剔除算法和基于稀疏矩阵的基线估计与降噪算法(BEADS),对粉煤灰样的全光谱数据进行了预处理。随机森林模型对粉煤灰熔点的预测平均相对误差(MRE)为54.74%,支持向量机回归模型的预测平均相对误差为60.08%,而线性回归模型的预测平均相对误差达到了9.78%。研究结果表明,线性回归模型对煤灰熔点的预测结果更准确。  相似文献   

4.
激光诱导击穿光谱对于宝玉石的定量分析一直是研究热点和难点,为了拓展激光诱导击穿光谱在宝石学研究与检测领域的应用,本文采用激光诱导击穿光谱(LIBS)对22个缅甸翡翠样品进行镁、钙含量的测量和分析,选取选择Ca(315.954 nm)、Mg (285.210 nm)和作为定标分析谱线,以Si(288.170 nm)光谱线作为内标谱线。以15个样品分别绘制出了基于谱线强度和基于谱线积分强度的MgO与CaO内定标曲线,基于谱线强度内定标法分析建立的MgO与CaO拟合曲线的相关系数R2分别为0.904和0.949,以检验集中7个样品检验定标曲线,MgO与CaO的LIBS测量值与参考值的相对偏差分别为9.43%-42.19%、4.067%-55.21%,与样品参考值的偏差分别优于0.47%、0.73%;而基于谱线积分强度内定标法分析建立的MgO与CaO元素拟合曲线的相关系数R2分别为0.947和0.973,以检验集中7个样品检验定标曲线,MgO与CaO的LIBS测量值与参考值的相对偏差分别为3.70%-34.91%、3.76%-37.28%,与样品参考值的偏差分别优于0.56%、0.49%。实验结果表明,基于谱线的积分强度的内定标法提高LIBS 检测翡翠中MgO与CaO的精确度。研究表明LIBS对翡翠样品的定量分析具有可靠的重复性和准确性,在宝石学研究领域具有重要的应用潜力。  相似文献   

5.
激光诱导击穿光谱(Laser-induced breakdown spectroscopy, LIBS)技术几乎不受聚变环境中的强磁场影响,是一种最有希望实现托卡马克装置中面向等离子体材料(Plasma facing materials, PFMs)原位在线诊断的技术,已被用于多个托卡马克PFMs壁诊断。然而,LIBS技术对PFMs表面元素的探测限、定量分析以及PFMs的服役状态判定依旧面临很大挑战。采用同轴飞秒-纳秒激光协同技术,建立了飞秒-纳秒双脉冲激光诱导击穿光谱(fs-ns-DP-LIBS)技术,通过高峰值功率、低激光能量的飞秒激光诱导等离子体,再用纳秒激光增强常规单脉冲LIBS技术信号发射强度,进而提升常规单脉冲LIBS的探测灵敏度,同时结合6种合金标准样品,采用fs-ns-DP-LIBS技术对样品中的主要元素进行了定量分析,并进一步结合机器学习方法对6种合金进行种类判别。结果显示:在纳秒单脉冲和飞秒单脉冲LIBS检测中,Ni、Fe和Mo在400~800 nm波段没有观察到明显特征峰,仅观察到Cr的特征峰;在飞秒-纳秒脉冲间2μs延时,NiⅠ498.02 nm、FeⅠ517....  相似文献   

6.
石油焦中微量元素对其作为预焙阳极的性能起着决定性的作用。首先,通过基于LIBS光谱构建用于石油焦中铁(Fe)和铜(Cu)定量分析的PLS校正模型。然后,考察了不同光谱预处理(归一化、多元散射校正、标准正态变换、一阶导数和二阶导数)以及变量选择算法(粒子群优化算法和变量重要性投影)对PLS校正模型预测性能的影响。建立了一种基于激光诱导击穿光谱(Laser-induced breakdown spectroscopy, LIBS)结合偏最小二乘(Partial least squares, PLS)的石油焦中微量元素定量分析方法。结果显示,与其他PLS校正模型相比,基于二阶导数和变量重要性投影的PLS模型对Fe的预测性能最优,最优的交叉验证相关系数(R-squared cross validation,R2cv)为0.966 7,均方根误差(Root mean squared error cross validation, RMSEcv)为10.282 1 mg/kg,预测集的相关系数(R-squared prediction,R2p)为0.86...  相似文献   

7.
中药材重金属元素快速检测对污染监控及人们健康具有重要意义。激光诱导击穿光谱技术(Laser Induced Breakdown Spectroscopy, LIBS)属于一种快速检测方法,研磨压片等预处理方法相对样品消解已有所简化,但破坏了样品的物理性质,且不能满足中药材大宗品种、大批量检测需求。若进一步简化样品预处理,将更加凸显LIBS快速检测的优势。本文建立了激光诱导击穿光谱技术(LIBS)快速微损检测中药材样品重金属元素定标方法。线性相关系数R2为0.7764,建立的微损定标曲线线性可用于切片党参LIBS快速检测,对待测党参切片样品检测平均相对误差为3.74%,与电感耦合等离子体质谱法(ICP-MS)对比,相关系数R2为0.7957,验证了LIBS技术微损检测的可行性。制备的党参参考定标样品可多次重复用于待测样定标和仪器标定等。实验对待测党参样品仅进行切片处理,避免了研磨、压片等预处理,更加充分地体现LIBS快速检测的优势,为LIBS技术应用于中药材重金属元素快检等领域提供了一种新方法。  相似文献   

8.
气溶胶是大气中的重要组分,对气候、生态环境等均有重要的影响。激光诱导击透光谱(LIBS) 在用于气溶胶检测时,由于气溶胶的离散分布,导致采集到大量无效光谱。本文提出一种结合字典学习对有效光谱数据进行筛选的方法——K-SVD-SVM。通过制备7种不同浓度的NaCl气溶胶样品,选取10% NaCl溶液的5000条光谱数据进行分类,其中70%作为训练集,30%作为测试集。当字典基向量数设置为3时,模型分类性能最优,准确率(accuracy),精确率(precision),召回率(recall),精确率和召回率的调和平均(F1)分别达到96%,95%,95%,0.95。此外,采用K-SVD-SVM方法对7种不同浓度的气溶胶样品进行筛选后,输入GA-ELM模型开展定量分析,同时将未筛选的原始光谱数据输入定量模型进行对比。未筛选的原始数据测试集RMSE和R2分别是0.0303和0.8726,筛选光谱后,分别提升至0.0187和0.9809。结果表明,K-SVD-SVM方法有着较好的分类性能,且采用此方法筛选出的有效数据可以为气溶胶中元素定量分析提供数据支撑。  相似文献   

9.
采用LIBS-OPA对取自不同电迁移部位的金属钆棒的纵剖面进行了原位统计分布分析,探讨了电迁移工艺中不同位置处的杂质元素在其电迁移方向上的分布规律。发现在电迁移工艺上部Ti和Cu的偏析较为严重,而下部即阴极附近的杂质元素含量大大降低且其分布趋于均匀。Ti和Al两个元素在电迁移末端含量发生较大变化,出现了一条明显的分界线,说明金属钆中的某些成分组成发生了突变,因此导致其分布发生了较大改变。而Cu,Si,Mo和Fe强度也都发生了不同程度的下降。但其偏析度变化不明显。Ti和Mo是金属钆的原位分析中出现异常信号较多的元素,说明金属Gd中存在一些Ti和Mo的化合物。采用透射电镜对金属钆棒中的化合物进行了观察,其结果与LIBS-OPA统计的结果较为相符。  相似文献   

10.
含油污泥中重金属元素的定量分析对石油石化工业区土壤环境污染情况的评估起着重要作用。首先,使用LIBS光谱仪采集30个含油污泥样品在200~500 nm波段的LIBS光谱,基于原始激光诱导击穿光谱(Laser-induced breakdown spectroscopy, LIBS)构建用于含油污泥中Cu、Cr和Pb三种重金属元素定量分析的初始随机森林(Random forest, RF)校正模型。然后,探究4种预处理方法,包括归一化(Normalization, Nor)、多元散射校正(Multivariate scattering correction, MSC)、一阶导数(First derivative, D1st)和二阶导数(Second derivative, D2nd)对基于原始LIBS光谱直接建立的RF模型预测性能的影响。以经过预处理后的LIBS光谱数据作为初始输入变量构建基于变量重要性(Variable importance measures, VIM)的RF校正模型,并采用袋外误差估计对变量重要性阈值进行了优化。最后,基于优化后阈值和变量数目构建了最优化的RF校正模型。结果表明,优化后的模型对预测集Cu、Cr和Pb三种元素的最优决定系数(Coefficient of determination, R2)分别为0.9801、0.9713和0.9736, 最优均方根误差(Root mean square error, RMSE)分别为0.0235 mg/kg、0.0283 mg/kg和0.0252 mg/kg。该研究可为石油石化工业区含油污泥重金属环境风险监测提供一定的理论与技术参考。  相似文献   

11.
Laser induced breakdown spectroscopy (LIBS) has become an analytical tool for the direct analysis of a large variety of materials in order to provide qualitative and/or quantitative information. However, there is a lack of information for LIBS analysis of agricultural and environmental samples. In this work a LIBS system has been evaluated for the determination of macronutrients (P, K, Ca, Mg) in pellets of vegetal reference materials. An experimental setup was designed by using a Nd:YAG laser operating at 1064 nm and an Echelle spectrometer with ICCD detector. The plasma temperature was estimated by Boltzmann plots and instrumental parameters such as delay time, lens-to-sample distance and pulse energy were evaluated. Certified reference materials as well as reference materials were used for analytical calibrations of P, K, Ca, and Mg. Most results of the direct analysis of plant samples by LIBS were in reasonable agreement with those obtained by ICP OES after wet acid decomposition.  相似文献   

12.
This paper investigates the optimization of double-pulse collinear femtosecond laser-induced breakdown spectroscopy (FLIBS) for silicon. Double-pulse FLIBS signal enhancements were observed over an extended range of sample focal plane position compared to single pulse FLIBS. The FLIBS signal intensity was studied as a function of pulse energy, inter-pulse delay (0 ps‑80 ps) and sample position. Correlation between crater volume and signal intensity was measured over a limited range of the sample focal plane position. It was found that double-pulse FLIBS is superior to single pulse for certain focal plane positions.  相似文献   

13.
We report on the development and implementation of analytical methodology for investigating elemental accumulation in different layers within plant leaves, with in-situ spatial resolution mapping, exploiting the technique of LIBS. The spectrochemical analysis of lead-doped leaf samples is demonstrated to develop a real time identification procedure in order to complement other analytical techniques not lending themselves for spatial resolution analysis. Our findings suggest that with elevated levels of Pb within the plants transportation and storage of some nutrition elements is changed.  相似文献   

14.
Glass samples of four types commonly encountered in forensic examinations have been analyzed by laser-induced breakdown spectroscopy (LIBS) for the purpose of discriminating between samples originating from different sources. Some of the glass sets were also examined by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Refractive index (RI) measurements were also made on all glass samples and the refractive index data was combined with the LIBS and with the LA-ICP-MS data to enhance discrimination. The glass types examined included float glass taken from front and side automobile windows (examined on the non-float side), automobile headlamp glass, automobile side-mirror glass and brown beverage container glass. The largest overall discrimination was obtained by employing RI data in combination with LA-ICP-MS (98.8% discrimination of 666 pairwise comparisons at 95% confidence), while LIBS in combination with RI provided a somewhat lower discrimination (87.2% discrimination of 1122 pairwise comparisons at 95% confidence). Samples of side-mirror glass were less discriminated by LIBS due to a larger variance in emission intensities, while discrimination of side-mirror glass by LA-ICP-MS remained high.  相似文献   

15.
Laser induced breakdown spectroscopy for bulk minerals online analyses   总被引:1,自引:0,他引:1  
The purpose of the work was to prove the ability of LIBS to provide on-line analyses for raw ores in field conditions. An industrial LIBS machine was developed and successfully tested for on-belt evaluation of phosphate measuring Mg, Fe, Al, Bone Phosphate Lime (BPL), Insoluble phase and Metal Impurity Ratio (MER) and of coal measuring its ash content. The comparison of LIBS on-line data with control analyses revealed good correlation, which corresponds to the required detection limits and accuracy. With frequent elemental data from a LIBS system, process engineers have the tools to best optimize the process. These processes could be minerals blending and separation to meet customer specifications, monitoring and controlling the efficiency of a minerals process, or a minerals accounting function.  相似文献   

16.
A review of recent results on stand-off Laser-Induced Breakdown Spectroscopy (LIBS) analysis and applications is presented. Stand-off LIBS was suggested for elemental analysis of materials located in environments where any physical access was not possible but optical access could be envisaged. This review only refers to the use of the open-path LIBS configuration in which the laser beam and the returning plasma light are transmitted through the atmosphere. It does not present the results obtained with a transportation of the laser pulses to the target through an optical fiber. Open-path stand-off LIBS has mainly been used with nanosecond laser pulses for solid sample analysis at distances of tens of meters. Liquid samples have also been analyzed at distances of a few meters. The distances achievable depend on many parameters including the laser characteristics (pulse energy and power, beam divergence, spatial profile) and the optical system used to focus the pulses at a distance. A large variety of laser focusing systems have been employed for stand-off analysis comprising refracting or reflecting telescope. Efficient collection of the plasma light is also needed to obtain analytically useful signals. For stand-off LIBS analysis, a lens or a mirror is required to increase the solid angle over which the plasma light can be collected. The light collection device can be either at an angle from the laser beam path or collinear with the optical axis of the system used to focus the laser pulses on the target surface. These different configurations have been used depending on the application such as rapid sorting of metal samples, identification of material in nuclear industry, process control and monitoring in metallurgical industry, applications in future planetary missions, detection of environmental contamination or cleaning of objects of cultural heritage. Recent stand-off analyses of metal samples have been reported using femtosecond laser pulses to extend LIBS capabilities to very long distances. The high-power densities achievable with these laser pulses can also induce self-guided filaments in the atmosphere which produce LIBS excitation of a sample. The first results obtained with remote filament-induced breakdown spectroscopy predict sample analysis at kilometer ranges.  相似文献   

17.
    
Here, the potential of laser-induced breakdown spectroscopy (LIBS) in grading calcareous rocks for the lime industry was investigated. In particular, we developed a system equipped with non-intensified detectors operating in scanning mode, defined a suitable data acquisition protocol, and implemented quantitative data processing using both partial least squares regression (PLS-R) and a multilayer perceptron (MLP) neural network. Tests were carried out on 32 samples collected in various limestone quarries, which were preliminarily analyzed using traditional laboratory X-ray fluorescence (XRF); then, they were divided into two groups for calibration and validation. Particular attention was dedicated to the development of LIBS methodology providing a reliable basis for precise material grading. The congruence of the results achieved demonstrates the capability of the present approach to precisely quantify major and minor geochemical components of calcareous rocks, thus disclosing a concrete application perspective within the lime industry production chain.  相似文献   

18.
In resonance-enhanced laser-induced breakdown spectroscopy, the sample was ablated by a laser pulse and the expanding plume was photoresonantly rekindled by a dye laser pulse. By sampling aluminum alloys for Mg, Pb, Si, and Cu, we showed that for the ablation step, Gaussian beams gave 2 to 3× better signal-to-noise ratio (SNR) than non-uniform beams. For the rekindling step, if no further sample destruction was allowed, dye laser pulses that intercepted the plume transversely gave 6 to 12× higher SNR than the longitudinal case. By combining Gaussian beams and transverse rekindling, the mass limit-of-detection for Mg was about 100 amol while non-resonant analysis was 10× more destructive. Sub-monolayer of oxides grown on laser-cleaned aluminum surfaces was detected by monitoring the AlO emissions of rekindled plumes; without resonant enhancements, they were not detectable no matter how destructive was the analysis. Time resolved studies showed that the Gaussian beam produced less dispersed plumes and that a stronger dye laser beam directed transversely heated up a bigger plume mass without over-heating the plume core. The analyte emissions were sustained while the continuum background remained low.  相似文献   

19.
Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) has been proposed several years ago as an approach for quantitative analysis of Laser-Induced Breakdown Spectroscopy spectra. Recently developed refinement of the spectral processing method is described in the present work. Accurate quantitative results have been demonstrated for several metallic alloys. However, the degree of accuracy that can be achieved with Calibration-Free Laser-Induced Breakdown Spectroscopy analysis of generic samples still needs to be thoroughly investigated. The authors have undertaken a systematic study of errors and biasing factors affecting the calculation in the Calibration-Free Laser-Induced Breakdown Spectroscopy spectra processing. These factors may be classified in three main groups: 1) experimental aberrations (intensity fluctuations and inaccuracy in the correction for spectral efficiency of a detection system), 2) inaccuracy in theoretical parameters used for calculations (Stark broadening coefficients and partition functions) and 3) plasma non-ideality (departure from thermal equilibrium, spatial and temporal inhomogeneities, optical thickness, etc.). In this study, the effects of experimental aberrations and accuracy of spectral data were investigated, assuming that the analytical plasma is ideal. Departure of the plasma conditions from ideality will be the object of future work. The current study was based on numerical simulation. Two kinds of metallic alloys, iron-based and aluminum-based, were studied. The relative weight of the error contributions was found to depend on the sample composition. For the here-investigated samples, the experimental aberrations contribute to the overall uncertainty on the quantitative results more than theoretical parameters. The described simulation method can be applied to the Calibration-Free Laser-Induced Breakdown Spectroscopy analysis of any other kind of sample.  相似文献   

20.
Results are reported on the application of double-pulse Laser-Induced Breakdown Spectroscopy (LIBS) for fast analysis of complex metallic alloys. The approach followed for the determination of the composition of the alloys is based on the time-integrated acquisition of LIBS spectra emitted by plasmas induced by collinear double-pulse laser excitation. The spectra are analysed using the Partial Least Squares method, which allows the determination of sample composition even in the presence of strong spectral interferences. The results shown indicate the possibility of measuring the composition of complex metallic alloys in very short times and using relatively cheap LIBS instrumentation.  相似文献   

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