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中红外反射光谱结合偏最小二乘法快速定量分析葡萄酒 总被引:5,自引:0,他引:5
利用傅里叶变换中红外光谱(FTIR)和衰减全反射(ATR)技术,结合偏最小二乘算法,建立了一种同时快速测定葡萄酒中总酚含量、滴定酸度、pH值和酒精度的方法。通过光谱预处理方法、异常值诊断和建模参数的优化,提高了模型的预测精度,各指标预测值与实测值相关性良好,总酚含量、滴定酸度、pH值和酒精度模型的相关系数(r2)依次为0.9356,0.9649,0.9935,0.9837;交互验证均方根误差(RMSECV)依次为:0.445,0.378,0.087,0.507。t检验结果表明模型预测结果与标准方法测定结果之间无显著性差异(显著性大于0.05)。 相似文献
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烟用香精对卷烟的香、吃味和质量稳定有重要影响,为了有效控制香精质量,降低卷烟主流烟气中有害元素的含量,采用密闭微波消解-电感耦合等离子体质谱法同时测定了烟用香精中铍、钒、铬、锰、镍、铜、锌、砷、硒、锶、钼、镉、铊和铅14种元素,方法的线性相关系数0.999 5~1.000 0,相对标准偏差1.3%~9.5%(n=5),检出限0.003~0.13μg.L-1,加标回收率88.1%~109.3%。结果表明方法能够满足微量元素的分析要求。用实验方法测定了38个牌号烟用香精中铍、钒等14种元素的含量。结果发现:(1)香精中锰、锌、锶的含量较高,硒、镍、铬、铜次之,铍、铊、钼、镉、钒、铅和砷的含量最低,其平均值均小于0.1μg.g-1。(2)锰、镉、锶的含量在不同香精之间差别较大,其变异系数分别为276.4%,238.7%,243.8%。 相似文献
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针对传统显著性模型在自然图像的显著性物体检测中存在的缺陷,提出了一种利用背景原型(background prototypes)进行对比的视觉关注模型,以实现显著性物体的检测与提取;传统显著性模型主要通过计算区域中心与四周区域差异性实现显著性检测,而自然场景中显著性区域和背景区域往往都存在较大差异,导致在复杂图像中难以获得理想检测效果;基于背景原型对比度的显著性物体检测方法在图像分割生成的超像素图基础上,选择距离图像中心较远的图像区域作为背景原型区域,通过计算图像中任意区域与这些背景原型区域的颜色对比度准确检测和提取图像中的显著性物体;实验结果表明,基于背景原型对比度的显著性模型可以更好地滤除杂乱背景,产生更稳定、准确的显著图,在准确率、召回率和F-measure等关键性能和直观视觉效果上均优于目前最先进的显著性模型,计算复杂度低,利于应用推广。 相似文献
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以TM影像对塔里木河中游土壤含水量的响应特征为研究对象,选取影像光谱(R)、光谱倒数(1/R)、光谱倒数之对数lg( 1/R)和去除归一化植被指数(Rc)四种光谱指标,分别建立土壤含水量的预测模型,并利用方差检验验证模型的显著性,采用后验差法划分模型精度级别.结果表明:光谱倒数之对数lg(1/R)预测土壤含水量的模型精... 相似文献
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借助近红外透射光谱技术得到香精样品的原始光谱,选取波段范围为8 800~8 540和7 500~5 085 cm-1,用主成分分析(PCA)法定性识别其中是否添加DEHP或DINP,正确率100%。同时测定了DEHP和DINP(浓度范围在0~100 mg·kg-1之间)在食用香精中的含量,并以偏最小二乘法(PLS)建立定量分析模型,DEHP和DINP预测结果的相对误差分别在-17.6%~15.8%和-7.6%~9.9%之间,预测均方根误差分别为1.39和0.98。为检测食用香精中增塑剂的含量提供了一种可同时定性与定量的快速、简便、廉价、准确的分析方法。 相似文献
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提出采用模糊近似熵的方法对功能磁共振成像(functional magnetic resonance imaging,fMRI)复杂度量化分析,并与样本熵进行比较.采用的22个成年抑郁症患者中,11位男性,年龄在18—65岁之间.我们期望测量的静息态fMRI信号复杂度与Goldberger/Lipsitz模型一致,越健康、越稳健其生理表现的复杂度越大,且复杂度随年龄的增大而降低.全脑平均模糊近似熵与年龄之间差异性显著(r=-0.512,p0.001).相比之下,样本熵与年龄之间差异性不显著(r=-0.102,p=0.482).模糊近似熵同样与年龄相关脑区(额叶、顶叶、边缘系统、颞叶、小脑顶叶)之间差异性显著(p0.05),样本熵与年龄相关脑区之间差异性不显著性.这些结果与Goldberger/Lipsitz模型一致,说明采用模糊近似熵分析fMRI数据复杂度是一个有效的新方法. 相似文献
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Dispersed fringe sensor(DFS) is an important phasing sensor of next-generation optical astronomical telescopes. The measurement errors induced by the measurement noise of three piston estimation methods for the DFS including leastsquared fitting(LSF) method, frequency peak location(FPL) method and main peak position(MPP) method, are analyzed theoretically and validated experimentally in this paper. The experimental results coincide well with the theoretical analyses.The MPP, FPL, LSF are used respectively when the DFS operates with broadband light(central wavelength: 706 nm,bandwidth: 23 nm). The corresponding root mean square(RMS) value of estimated piston error can be achieved to be1 nm, 3 nm, 26 nm, respectively. Additionally, the range of DFS with the FPL can be more than 100 μm at the same time. The FPL method can work well both in coarse and fine phasing stages with acceptable accuracy, compared with LSF method and MPP method. 相似文献
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针对口径天线及其近区任意厚均匀介质体的复杂系统,应用表面积分方程(SIE)方法结合模式匹配方法(MM)建立了模式激励的新型一体化电磁模型。在馈电端口采取模式匹配方法模拟了波导中的激励情况,将金属壁处理为理想导电体,并在金属壁上利用边界条件建立电场积分方程(EFIE);利用零场等效原理在介质体内外表面分别建立电场积分方程和磁场积分方程(MFIE),并组合内外表面建立的电场积分方程和磁场积分方程为PMCHW方程;最后使用矩量法对所建立的EFIE-PMCHW-MM组合方程进行求解。文中结合喇叭天线设计了两个典型算例,所提混合方法EFIE-PMCHW-MM给出的数值结果与商用软件FEKO高度一致,且在求解口径天线与近区厚介质体耦合问题时由于未知量显著减少,大幅度提高了仿真效率,降低了计算机资源消耗。 相似文献
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The variational-cumulant expansion method has been extended to SU(3) mixed-action lattice gauge theories. By using the method, the phase diagrams of SU(3) mixed model are obtained in four and five dimensions. The results are in good agreement with the Monte Carlo results. The comparison with results of the mean field method and the mean plaquette method is abo given. 相似文献
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Two different order reduction methods of the deterministic and stochastic systems are discussed in this paper. First, the transient proper orthogonal
decomposition (T-POD) method is introduced based on the high-dimensional nonlinear dynamic system. The optimal order reduction conditions of the T-POD
method are provided by analyzing the rotor-bearing system with pedestal looseness fault at both ends. The efficiency of the T-POD method is verified via comparing with the results of the original system. Second, the polynomial dimensional
decomposition (PDD) method is applied to the 2 DOFs spring system considering
the uncertain stiffness to study the amplitude-frequency response. The numerical
results obtained by the PDD method agree well with the Monte Carlo simulation
(MCS) method. The results of the PDD method can approximate to MCS better
with the increasing of the polynomial order. Meanwhile, the Uniform-Legendre
polynomials can eliminate perturbation of the PDD method to a certain extent
via comparing it with the Gaussian-Hermite polynomials. 相似文献
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The frequency dependence on the reflectance of a one-dimensional (1D) photonic crystal composed of repetitive metallic and
dielectric layers was simulated by the finite difference in the time domain (FDTD) method, and with results compared to the
conventional transfer matrix (TM) method. The simulation from the FDTD method with an impedance-matched boundary of finite
dimensions yields results similar to the calculation from the TM method with unbounded planes. The FDTD method is prominent
in dealing with films of finite area including defects at some locations. The reflectivity increases and the rejection bandwidth
decreases as the number of layers increases.
PACS 42.70.Qs; 47.11.Bc; 78.20.-e; 78.67.-n 相似文献
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R. S. Chen D. X. Wang Edward K. N. Yung 《International Journal of Infrared and Millimeter Waves》2002,23(2):275-293
The multifrontal method is applied for solving a large system of linear equations resulting from the use of edge-based finite element method (FEM). The finite element method combined with the perfectly matched layers (PML) is given for simulation of microwave filters and the algorithm of multifrontal method is described in detail. The reflection and insertion losses of millimeter wave filter are analyzed as the examples and the obtained results are compared with those obtained from literature. In order to demonstrate the efficiency of the multifrontal method, the computational time is compared with that of both symmetric successive overrelaxation (SSOR) preconditioned conjugate gradient (PCG) and conjugate gradient methods (CG) for the thick-iris waveguide bandpass filer. 相似文献
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利用网络分析仪,根据需要在设定的频率范围进行扫频测量,网络分析仪的端口1输出的微波信号经过微波传输转换器进入与待测非标准元件匹配连接的连接段(如波导);网络分析仪的端口2连接定向耦合器,用于监测传输段内的反射微波信号。首先,在非标准接口端面连接短路面,通过网络分析仪测量反射信号在设定频点的相对幅度值;然后去掉短路面,在非标准接口端面连接待测元件,再次测量反射信号在特定频点的相对幅度值;最后根据本文推导的公式得出驻波系数。该方法的测量误差与定向耦合器的方向性(方向性系数越大越好)和待测元件驻波系数有关。将该方法运用在非标准接口匹配负载驻波系数的测量中,定向耦合器方向性系数取为40 dB,测得其驻波系数小于1.2,误差小于20%。该方法简便可行,可以用于测量常用的非标准接口元件尤其是非标准低驻波系数元件的驻波系数。 相似文献
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利用网络分析仪,根据需要在设定的频率范围进行扫频测量,网络分析仪的端口1输出的微波信号经过微波传输转换器进入与待测非标准元件匹配连接的连接段(如波导);网络分析仪的端口2连接定向耦合器,用于监测传输段内的反射微波信号。首先,在非标准接口端面连接短路面,通过网络分析仪测量反射信号在设定频点的相对幅度值;然后去掉短路面,在非标准接口端面连接待测元件,再次测量反射信号在特定频点的相对幅度值;最后根据本文推导的公式得出驻波系数。该方法的测量误差与定向耦合器的方向性(方向性系数越大越好)和待测元件驻波系数有关。将该方法运用在非标准接口匹配负载驻波系数的测量中,定向耦合器方向性系数取为40 dB,测得其驻波系数小于1.2,误差小于20%。该方法简便可行,可以用于测量常用的非标准接口元件尤其是非标准低驻波系数元件的驻波系数。 相似文献