Accuracy improvement of calibration-free laser-induced breakdown spectroscopy

Calibration-free laser-induced breakdown spectroscopy can overcome the matrix effect and the huge application prospects of in situ and on-line measurement, so it has been studied and applied to many analytical samples by numerous researchers since it was first proposed in 1999.However, its accuracy is always lower than other analytical techniques and traditional quantitative analysis methods of laser-induced breakdown spectroscopy. The goal of this paper is to review the improvement of accuracy in the experimental setup and spectral analysis,especially after 2010, but not limited to it. The main contents include the accurate measurement of spectral intensity, the spatial and temporal window of local thermodynamic equilibrium and the accurate calculation of temperature and electron density. Due to the requirement of one or more standard samples, the combination of standard samples and CF-LIBS is discussed as a separate section. Finally, a simple conclusion is offered to relevant researchers who want to use CF-LIBS for quantitative analysis.     

稀土材料的研究与应用展望

本文对稀土元素及其性质进行了综述,并对稀土材料的研究与应用展望情况进行了详细的介绍.     

激光诱导击穿光谱表征3D打印18Ni300模具钢表面硬度

3D打印零件的表面硬度直接影响着其后续的运行安全和使用寿命,目前硬度的测量依赖于破坏性取样后的实验室分析,缺少无损和在线的硬度测量方法。采用激光诱导击穿光谱技术研究了3D打印18Ni300模具钢表面硬度和光谱特性与等离子体特性的关系。得到了样品表面硬度和离子谱线与原子谱线的强度比以及表面硬度和等离子体温度之间的线性关系,离子与原子谱线的强度比和等离子体温度均随着表面硬度的增加而增大。实验结果证明了激光诱导击穿光谱技术作为一种近无损和在线表征3D打印零件表面硬度的方法的可行性。     

苹果酯的合成及其应用

概述了苹果酯的性质,应用。以柠檬酸化催化剂,使乙酰乙酰乙酸乙酯和乙二醇反应合成苹果酯,并确定了最佳反应条件。     

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

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.     

集成微区成像的激光诱导击穿光谱系统的光谱信号稳定性分析

搭建了一套集成微区成像的激光诱导击穿光谱系统,运用描述性统计分析方法分析了激光器的能量稳定性、光谱仪的噪声水平,重点分析、对比了气体样品和固体样品激光诱导击穿光谱信号的稳定性特征。结果表明:空气样品激光诱导击穿光谱信号具有明显的随机波动特性和正态分布特征,铝合金样品激光诱导击穿光谱信号具有明显的位置敏感特性和非随机波动特性;与空气样品相比,铝合金样品激光诱导击穿光谱信号的不稳定性主要源于光与物质相互作用区域的变化;对具有正态分布特征的激光诱导击穿光谱信号,可通过多脉冲平均来有效提高其稳定性。     

矿物掺合料对水泥砂浆强度和早期开裂的影响

综合评价了粉煤灰、硅粉对水泥砂浆早期收缩开裂和强度的影响,进一步研究了粉煤灰、硅粉对砂浆自由收缩、初始开裂时间以及初始开裂时抗折强度的影响,在本试验材料体系内,优化出开裂敏感性相对较优的水泥基材料组成。     

粉煤灰特性及其在绿色高性能混凝土中的试验研究

主要分析了粉煤灰的组成、结构与作用机理,介绍了各国有关粉煤灰的标准,研究了粉煤灰高性能混凝土的力学性能、抗渗性能及其微观形貌。结果表明,绿色高性能混凝土中掺入粉煤灰,在满足和易性和力学性能的基础上,可以提高其耐久性;掺入粉煤灰可以显著改善混凝土中骨料与浆体的界面过渡区,有利于提高其抗渗性能和力学性能。     

光伏晶硅切割用超细高强高碳钢丝的铅浴等温淬火工艺研究

利用电子扫描电镜、拉伸仪、耐疲劳性能试验机等分析测试方法研究铅浴等温淬火工艺对超细高强高碳钢丝组织和力学性能的影响。结果表明:对含碳量0.92%、直径Φ0.84mm的钢丝,升高加热温度、降低铅浴温度、提高过冷度有利于奥氏体化均匀,促进珠光体转变,导致先共析铁素体和二次网状渗碳体减少、珠光体片层间距减小、晶粒尺寸约20～30μm,后道湿拉拔至直径Φ0.12mm,断丝率降低至4～7次/t,钢丝最终强度达4080MPa。     

PLC系统抗干扰性能探讨

本文分析了PLC控制系统中干扰信号的主要来源,从PLC的设备选型、安装、电源、接地等诸方面,介绍有效的抗干扰措施。