共查询到19条相似文献,搜索用时 46 毫秒
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提出了犯罪现场常见的塑料快递包装袋物证的识别分类模型。利用X射线荧光光谱法对60个不同产地和品牌的塑料快递包装袋样品进行了元素种类及含量的检验,并依据光谱数据进行了定性半定量分析,将60个样品初步分成13类。探究了簇内误差平方和(SSE)与聚类数的关系,并确定最优聚类数为6,利用K-means算法将60个样品成功聚成了6类,最后对聚类结果进行了Fisher判别分析。经检验,60个样品的原始分类正确率和交叉验证后的分类正确率分别为98.3%和91.7%,验证了基于K-means和SSE的塑料快递包装袋样品识别分类模型的准确性与科学性。基于X射线荧光光谱法、K-means和SSE,所提模型能无损、快速且有效地检验及识别分类塑料快递包装袋物证,结果准确可靠。 相似文献
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为了对塑料饮料瓶物证进行检验分析,利用傅里叶变换红外光谱仪、X射线荧光光谱仪和厚度仪,对57个塑料饮料瓶样品进行抽查检验,并结合聚类分析方法进行了分析处理。首先,红外光谱法可对塑料饮料瓶样品的主要成分进行检验,根据样品成分的不同,可分为聚乙烯(PE)和聚对苯二甲酸乙二醇酯(PET)两大类;其次,通过X射线荧光光谱法对样品中的主要填料碳酸钙进行测定,根据Ca元素的含量可以对样品进行区分;最后,利用测厚仪可对塑料饮料瓶样品的厚度进行测定。根据样品的颜色、规格、成分、Ca元素的含量以及样品的厚度,结合聚类分析法可以将样品进行区分,实验结果表明该方法简便快速、结果准确可靠、且无损检材,可用于检验区分塑料饮料瓶。 相似文献
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采用红外反射光谱技术对珠宝市场上的六种塑料仿宝石饰品进行了测试研究,并将其与相应被仿宝石(粉珊瑚、象牙、红纹石、绿玉髓、水晶和合成黑欧泊)进行了对比分析。结果表明,由于物质成分及分子结构的不同,塑料仿制品与真实宝石的红外图谱差异显著。该项技术不仅能够依据红外谱峰的数量、峰位、形态、强度以及谱带分裂状态等特征对塑料进行鉴别及归类,而且还是一种快速、准确、无损的塑料仿制品检测手段。尤其是针对外观及基本物性特征与真实宝石相差无几的塑料高仿制品(如仿合成黑欧泊),常规技术手段无法鉴别,但红外反射光谱技术则可发挥无可替代的作用。 相似文献
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红外光热吸收效应作为一种无损伤非接触的检测技术,已经被广泛用于硅等半导体材料中的微缺陷表征分析.采用光热吸收技术对碲锌镉晶体中的缺陷进行扫描成像分析时发现了一种连续性的光貌相条纹,并对这些条纹的形成机理进行了研究.研究表明碲锌镉晶体中的这种连续性条纹源自于光热测试系统中入射光的干涉,这种干涉和入射光参数、测试样品的厚度、禁带宽度以及热导率等材料特性密切相关.最后,实验通过优化红外光热吸收测量系统获得了碲锌镉材料中的微缺陷结构及其在样品深度方向的三维分布图像. 相似文献
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R. Sudharsanan Z. C. Feng S. Perkowitz A. Rohatgi K. T. Pollard A. Erbil 《Journal of Electronic Materials》1989,18(3):453-455
Single crystal Cd1−x
Mn
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Te (x=0.10–0.30) films have been grown by metalorganic vapor deposition (MOCVD) on (111) GaAs substrates with and without CdTe
buffer layers, at substrate temperatures of 380° to 450° C. Infrared phonon spectra reveal that the films grown at 420° C
substrate temperature have reasonable Mn concentration (>10%) and are of good quality in agreement with Raman measurements.
Spectral analysis also gives values for Mn concentration that agrees with photoluminescence measurements, and determines film
thickness. 相似文献
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病害烟叶的傅里叶变换红外光谱研究 总被引:3,自引:1,他引:2
利用傅里叶变换红外光谱法研究了正常烟叶和四种病害烟叶,结果显示,它们的红外光谱主要由蛋白质、脂类化合物及多糖的振动吸收谱带组成。烟叶光谱整体相似,仅在1800~750 cm-1范围,正常烟叶和病害烟叶的光谱峰位、峰形及吸收强度比有一定差异。为了提高光谱灵敏度,对光谱进行二阶导数相关性分析,五个样品的二阶导数光谱在1750~1500 cm-1和1200~950 cm-1范围内的相关系数差异明显,表明五种烟叶样品所含化学成分或各成分相对含量各不相同,即病害影响烟叶的化学成分。正常烟叶的吸收强度比A1025/ 相似文献
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We have designed a Zeeman-tuned laser oscillating at nearly all laser transitions between 3 and 9 μm, and we have studied absorption bands between 1250 and 1450 cm-1where many xenon and neon laser lines have sufficient gain to allow displacements of 0.1 cm-1The apparatus is an internal-mirror discharge, dc excited, on a granite bench well isolated from mechanical vibrations. The Fabry-Perot cavity is 1.66 meter. Applied axial magnetic fields vary from 0 to 1800 Gs. The circular polarizations are converted to linear perpendicular polarizations by a quarter-wave plate consisting of a Fresnel prism. The laser beam, after passage through the absorption cell, is detected by a Ge-Au cell behind a monochromator. The detected signal and the magnetic field are simultaneously recorded by anXY recorder. 相似文献
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D. G. Mead S. R. Lowry C. R. Anderson 《Journal of Infrared, Millimeter and Terahertz Waves》1981,2(1):23-34
Infrared spectra in the 100–15000 wavenumber region (0.67–100 μm) of some ionic (as LiF) and semiconducting (as Ge, Si, GaAs) powders and crystals are reported. The experiment involves the use of a photoacoustic cell as an accessory to a multiple scan averaging Michelson interferometer. The results show the advantages of studying impurities in powders, and surface properties, particularly since the technique is immune to scattering induced errors. 相似文献
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Zhen-Hong Zhou Compton S. Yang I. Reif R. 《Semiconductor Manufacturing, IEEE Transactions on》1994,7(1):87-91
The results of a novel emission Fourier transform infrared (E/FT-IR) spectrometer for in-situ characterization of semiconductor materials is presented. For the experiments, the wafers were heated and the infrared emission profiles from the substrates were collected by a standard FT-IR spectrometer. Differences in the emission spectra from different substrates are explained through correlation to the optical properties of the corresponding substrates. The in-situ infrared emission spectrum of a lightly doped (10-20 Ω·cm) silicon wafer at 200°C is very similar to its ex-situ transmission spectrum at room temperature, although the spectrum is inverted. This similarity makes possible the analysis of E/FT-IR spectra by using existing spectral libraries. Finally, it is shown that the E/FT-IR technique can be used for noncontact and noninvasive real-time identification and possibly quantification of impurities during silicon oxidation and for real-time epi-film thickness monitoring during silicon epitaxy 相似文献
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乙醇汽油含量的近红外光谱检测研究 总被引:1,自引:0,他引:1
随着石油资源的匮乏和能源需求量的日益增大,乙醇作为一种替代车用燃料越来越受到重视。在调和乙醇汽油的过程中由于其辛烷值的波动较大,影响车辆的动力性能,因此对乙醇汽油中的乙醇含量的准确检测具有重要意义。利用近红外光谱分析技术(NIR)定量分析乙醇汽油中的乙醇含量。实验结果表明,利用PCA在光谱1840~2030 nm范围能够准确分类乙醇汽油和成品汽油;采用PLS在光谱1400~2200 nm范围准确测量乙醇汽油中的乙醇含量,其交叉检验均方根误差(standard error of cross validation,SECV)为1.35(%,V/V),可以满足大部分乙醇汽油生产企业的实际检测需求。因此,采用近红外光谱技术和PCA,PLS分析方法可以有效的对乙醇汽油和成品汽油进行分类,对乙醇含量的定量分析模型也可以达到较高的精度。 相似文献
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R. Nies F. R. Kessler U. Scheuermann H. Luka 《Journal of Infrared, Millimeter and Terahertz Waves》1990,11(2):227-242
An optical method is presented for thenon-destructive electrical and structural characterisation of multilayer structures. The presented concept yields the complex refractive index profiles within an arbitrary composed layer system by using the symmetrical transmission and the asymmetrical reflectivity caused by the optical inhomogeneity of a material. This method includes the superimposition of coherent multiple reflections within the refractive index profile as well as incoherent multiple reflections within the whole wafer. This analysis yields the spacial distribution of free carrier density profiles within the sample as well as the transitions between different crystal phases by using the least squares fit procedures. The results of the optical analysis are compared with other methods used to quantitatively determine density profiles and phase transitions such as SIMS, spreading resistance, stripping Hall and RBS. 相似文献
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Mendelson Y. Clermont A.C. Peura R.A. Lin B.-C. 《IEEE transactions on bio-medical engineering》1990,37(5):458-465
The difficulty of measuring physiological concentrations of glucose in blood by conventional infrared absorption spectroscopy is due to the intrinsic high background absorption of water. This limitation can be largely overcome by the use of a CO2 laser as an infrared source in combination with a multiple attenuated total reflection (ATR) technique. To demonstrate the applicability of this technique, we compared in vitro measurements of glucose in blood obtained from an experimental infrared laser spectrometer with independent measurements made by a standard YSI 23A laboratory glucose analyzer. The capability of continuous measurement of blood glucose concentration is of primary importance in the future development of a glucose sensor for diabetic patients. 相似文献