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在对乙醇、甲醇等醇类溶液荧光光谱特性进行研究的基础上, 应用美国Roper-Scientific公司SP-2558多功能光谱测量系统, 对50多种品牌白酒及其年份酒在紫外光激励下的荧光光谱进行了检测。结果表明, 白酒在紫外光激励下能产生较强的荧光, 各品牌白酒及其年份酒的荧光光谱各有明确的特征。实验测得其三维荧光光谱, 由此构建了白酒荧光光谱指纹图库。分析各荧光光谱的特征, 以谱峰个数、峰值波长、最佳激励波长等特征值创建了各品牌年份白酒荧光光谱特征数据库。利用SQL 数据库软件和VB语言研制成一个能对白酒进行自动比对、识别的白酒荧光光谱智能鉴别系统,实现了白酒的智能化鉴别。研究结果发挥荧光光谱分析灵敏度高、准确度高和样品用量少、不需前期处理等优点, 为白酒检测、鉴别提供了一种有效的新方法, 能应用于白酒企业生产管理及白酒消费市场监督, 并为已引起广泛关注的酒类食品安全监管提供帮助。 相似文献
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The effective dielectric response of the composites in which nondilute coated metal particles are randomly embedded in a linear host is investigated. Two types of coated particles are considered, one is that the core is nonlinear, the other is that the shell is nonlinear. We derive general expressions for the effective linear dielectric function and the effective third-order nonlinear susceptibility, and take one step forward to perform numerical calculations on the coated metal/dielectric composites. Numerical results show that the effective linear and nonlinear dielectric responses can be greatly enhanced near the surface plasmon resonant frequency. Moreover, the resonant peaks are found within a range from 0.46ωp to 0.57ωp for spherical particles and from 0.59ωp to 0.70ωp for cylindrical inclusions. In the frequency region, the resonant peak can achieve the maximum, according to an optimal structural parameter and volume fraction. The resonant frequency exhibits a redshift with the increasing structural parameter k or volume fraction f or dimensionality factor D. 相似文献
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基于荧光光谱和径向基函数神经网络的合成食品色素测定和鉴别 总被引:1,自引:0,他引:1
以合成食品色素胭脂红、苋菜红溶液为例,提出了应用荧光光谱结合径向基函数神经网络对合成食品色素溶液进行浓度测定和种类鉴别的方法。应用SP-2558多功能光谱测量系统,测得胭脂红和苋菜红溶液分别在波长为300和400 nm的光激发下产生的荧光光谱。对每个胭脂红溶液样本选取15个发射波长值所对应的荧光强度作为网络特征参数,训练、建立用于浓度预测的径向基函数神经网络。据此,对3种胭脂红溶液样本的浓度进行预测,预测结果相对误差分别为1.42%,1.44%和3.93%。另外,以胭脂红和苋菜红溶液荧光波长值所对应的荧光强度作为特征参数,训练、建立了用于种类鉴别的径向基函数神经网络,进行合成食品色素溶液种类识别,准确率达100%。这些结果表明,该方法方便、快捷、准确度较高,可应用于合成食品色素检测及食品安全监管。 相似文献
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Revivals of Zitterbewegung in the Bernevig Hughes Zhang model in the quantum spin Hall regime with a laser pulse 下载免费PDF全文
We theoretically investigate the Zitterbewegung (ZB) behavior of electrons in the Bernevig-Hughes-Zhang model with a short laser pulse. To obtain a steady picture, we fix the electron on the Landau levels with a magnetic field. The ZB motion and the electromagnetic radiations in the quantum spin Hall regime are given. We find that over a shorter time, the electromagnetic radiations show a quasi-classical cyclotron oscillation, while over a longer time, they exhibit a clear revival picture. The resulting revival time and excited electric field are large enough to make experimental detection accessible. 相似文献
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应用非线性微分有效偶极近似方法,导出了关于非线性梯度圆柱颗粒的等效线性介电常数和三阶非线性极化率的微分式,研究了稀释极限下,圆柱形梯度颗粒无规置入线性介质中组成的复合介质的有效线性介电常数和三阶非线性极化率.作为应用,数值计算了具有幂指数梯度分布的介电常数的颗粒复合介质的有效非线性响应,及梯度金属电介质颗粒复合介质的表面plasmon共振效应. 相似文献