可见-近红外高光谱图像技术快速鉴别激光打印墨粉

为了使用快速、无损的方法区分激光打印文件使用的墨粉种类,利用高光谱成像技术结合化学计量法对6种激光打印墨粉的光谱数据进行建模和种类鉴别的研究。利用可见-近红外高光谱成像仪采集400~1 000 nm波段内的光谱数据,采用Savitzky Golay平滑、标准化、多元散射校正和标准正态变量变换4种方法分别对光谱数据进行预处理,而后分别建立随机森林(RF)、K最近邻(KNN)、支持向量机(SVM)、偏最小二乘判别分析(PLS-DA)和簇类独立软模式(SIMCA)模型,进而实现激光打印墨粉的种类鉴别。利用准确率、拒识率和误识率3个指标作为模型评价标准。实验结果显示,SVM和PLS-DA模型的效果最佳,准确率为100%,拒识率和误识率为0。基于可见-近红外高光谱成像技术可以实现激光打印墨粉的快速种类鉴别。     

建立支持向量机SVM识别模型对翡翠产地进行识别

为了实现翡翠产地的快速无损鉴别,丰富宝玉石产地鉴别方法的多样性,基于红外光谱分析得到的数据,建立支持向量机(SVM)识别模型对三个产地的翡翠进行分析。实验收集了缅甸、俄罗斯和危地马拉3种翡翠的红外光谱数据共106条,为了达到更好的模型识别效果,建模前将原始的红外光谱数据进行反射率到吸光度的转化,再对光谱进行不同的预处理。预处理的目的是降低噪声、基线漂移和散射现象等对模型识别效果的影响。本次实验预处理使用的方法有SG平滑、均值中心化、标准化、趋势校正、多元散射校正、最大最小归一化、标准正态变换以及标准正态变换后再进行趋势校正。实验结果表明,对红外光谱进行预处理后模型得到的识别准确率均高于原始光谱的73%;三个产地翡翠的红外光谱分开进行多元散射校正和最大最小归一化得到的模型识别准确率高于混合进行预处理得到的结果;一些预处理方法结合使用也会提高模型的识别准确率,如标准正态变换和趋势校正。对三个产地翡翠的红外光谱分开进行最大最小归一化处理后得到的识别准确率达到了最高的95%,说明这种采用红外光谱技术建立的支持向量机(SVM)识别模型可以实现对翡翠产地的快速识别。     

子宫内膜癌组织近红外光谱预处理与波段选择研究

应用近红外光谱技术对子宫内膜组织病理切片进行快速无损检测。收集了154样品光谱,其中正常样本的个数36个,增生的60个,癌变的58个。由于原始光谱中包含大量干扰信息,所以光谱预处理方法和波段选取的方法在近红外光谱分析中占有非常重要的地。利用多种预处理方法,包括一阶导数、多元散射校正、多项式最小二乘拟合求导、标准归一化、平滑、移动窗口中值滤波,对样品光谱进行了预处理。利用标准偏差谱来选取最优波段,选取的最优波段范围为4 000~6 000 cm-1。然后用处理后的光谱数据进行主成分分析,分类准确率达到100%。研究结果表明近红外光谱技术结合化学计量学方法可以作为一种癌症快速诊断的新技术,对于癌症的早期诊断和癌症组织的恶化过程研究具有重要的意义。     

近红外漫反射光谱无损检测乳粉蛋白质的研究

利用近红外漫反射光谱技术对奶粉蛋白质含量的快速无损检测进行了研究。挑选来自国内不同地区的29种奶粉,以化学分析值作参比,采用偏最小二乘回归算法建立奶粉光谱信息和蛋白质含量的定量模型,预测均方根差(RMSEP)为0.687%。采用波长选择对模型进行优化后,波长点从1 558个减为11个,大大加快了运算速度,同时还在一定程度上提高了模型的精度。为了减小颗粒大小不均匀和粒子表面非特异性散射的影响,对光谱数据进行了标准正态变量(SNV)变换和多元散射校正(MSC),结果表明这两种方法是有效的,得到RMSEP减小了约37%。研究结果表明,近红外漫反射光谱测定奶粉中蛋白质含量实时、快速,能满足工业过程分析中的测量精度要求,为提高奶粉质量分析水平提供了新的途径。     

近红外漫反射光谱法测定整粒小麦单株蛋白质含量

应用近红外漫反射光谱技术(波长为1 100～2 498 nm,分辨率为2 nm),以整粒小麦为材料建立适合于小麦单株分析的蛋白质含量分析系统。首先选取籽粒蛋白质含量具有梯度差异的小麦样品,然后对样品扫描得到原始光谱信息,通过散射校正及数学处理来消除原始光谱噪声,最后分别采用多元线性回归、主成分分析法和偏最小二乘法法建立回归方程。结果表明,优化各项参数后,光谱经过标准乘性散射校正和一阶导数处理后,回归分析采用修正的偏最小二乘法(MPLS)得到的定标模型效果最佳。最终得到的预测方程定标相关系数(RSQ)、交叉验证标准误差(SECV)、交叉验证相关系数(1-VR)分别为0.94,0.42,0.87。数学模型经过验证样品集检验,预测相关系数达到0.88。该模型达到了快速、无损分析单株小麦的要求,非常适合于品质育种的早代选择。     

近红外光谱法的甜菜糖度快速测定

为了实现甜菜依据含糖量定等分级,甜菜收购环节的按质论价,促进甜菜制糖行业的良好健康发展,应用近红外光谱技术对甜菜糖度的快速检测进行了系统研究,确定了一种快速、无损、准确的测量甜菜糖度的方法。采集具有代表性的28个甜菜品种,820个甜菜样品作为校正集,70个样品作为预测集,扫描得到甜菜校正集样品的近红外原始光谱,选择合适的光谱预处理方法,采用偏最小二乘法建立甜菜糖度的定量预测数学模型,以校正模型的内部交互验证均方根误差(RMSECV)、决定系数(R2)和外部预测标准误差(SEP)为指标对模型的性能进行评价,并对模型的预测效果进行了比较。采用一阶导数和标准正态变量变换对光谱进行预处理并结合偏最小二乘法所建立的定量预测数学模型的预测能力较好。甜菜糖度定量校正数学模型的模型决定系数为0.908 3,内部交互验证预测均方根误差为0.376 7。用此数学模型对预测集70个样品进行预测,预测值与实测值的相关系数达到0.921 4,预测标准误差为0.439,预测值和实测值之间不存在显著性差异(p＞0.05)。结果表明：近红外光谱法作为一种简单、快速、无损、环保的检测方法,能够良好的评价甜菜的糖度。建立的模型具有很高的精确性,可以满足甜菜糖含量测定的需要,该方法可以实现甜菜收购环节的定等分级和按质论价。     

高光谱成像技术鉴别菠菜叶片农药残留种类

利用高光谱成像技术无损鉴别菠菜叶片农药残留种类。采用高光谱成像仪采集900~1 700 nm波段内的光谱数据,采用多元散射校正对光谱数据进行预处理。利用主成分分析对不同种类菠菜样品的光谱数据进行分析,结果表明主成分分析能在可视化层面对不同种类的农药残留菠菜样品进行有效判别。另外,将卡方检验特征选择算法分别与支持向量机、朴素贝叶斯、决策树和线性判别分析算法结合,并采用10-fold交叉验证评价方法,筛选出最佳波段和最优判别模型（线性判别模型）。筛选出的8个特征波长为1 439.3,1 442.5,1 445.8,1 449,1 452.3,1 455.5,1 458.7,1 462 nm,模型的预测准确率达到0.993且10次交叉验证的标准差为0.009。结果表明,基于高光谱成像技术能准确地识别菠菜叶片上的农药残留种类。     

红外光谱法与荧光光谱成像技术结合神经网络对正毛化橘红的快速鉴别

为探究一种快速、可靠的化橘红检测方法,本实验分别采用傅里叶变换衰减全反射红外光谱法和荧光光谱成像技术结合多层感知器(MLP)神经网络所构建的模式识别方法,对化橘红进行鉴别,并对两种方法进行了比较。实验以81个正毛化橘红,37个其他品种橘红共118个样品为研究对象,采集所有样品的红外光谱和荧光光谱图像。根据光谱曲线中不同样品间的差异,取红外光谱中550-1800 cm-1区段范围内的光谱数据和荧光光谱曲线中的400～720 nm区段的光谱数据进行分析,应用主成分分析法(PCA)对化橘红的光谱数据进行降维处理,再结合MLP神经网络对化橘红样品进行判别分析。实验中分别使用多元散射校正(MSC)、标准正态变量校正(SNV)、一阶导(FD)、二阶导(SD)以及Savitzky-Golay(SG)平滑数据预处理方法,并比较他们对鉴别模型的影响。分析结果表明：利用红外光谱法(FTIR/ATR),经由Savitzky-Golay(SG)平滑预处理得到的数据,通过隐层函数为sigmoid的三层MLP模型,能够得到最优正毛化橘红识别率,其结果训练集和测试集的识别率都为100%;利用荧光光谱成像技术,由多元散射(MSC)预处理的结果是最理想的。经过预处理的数据,通过隐层函数为sigmoid函数的三层MLP模型,训练集识别率达到100%,测试集识别率达到96.7%。由此可见,衰减全反射红外光谱法(FTIR/ATR)和荧光光谱成像技术分别与MLP神经网络构建的识别模式,均可对化橘红的判别达到快速、可靠的效果。     

基于近红外光谱技术快速无损检测大豆含水量

为了研究近红外光谱法快速无损检测大豆含水量的可行性,在室内通过FieldSpec4高分辨地物光谱仪对100份大豆样品进行光谱数据测量,经过平滑、求导、多元散射校正等七种不同的光谱预处理变换之后,利用主成分回归分析方法(PCR)和偏高最小二成回归分析方法(PLSR)分别建立大豆含水量高光谱估测模型。结果表明,基于原始光谱的一阶导变换建立的偏最小二成回归模型预测精度最高,其校正集和预测集的相关系数和均方根误差分别为R_c~2=0.74、R_p~2=0.85,RMSE_c=0.30,RMSE_p=0.45,近红外光谱技术可用于快速无损检测大豆含水量。     

多位置可见/近红外光谱检测与种鸡蛋受精信息的关系研究

种鸡蛋孵化过程耗时、耗能,但种蛋由于未受精导致胚胎发育率不足100%,种鸡蛋孵化早期快速判别,可有效提高种蛋孵化效率和降低经济损失。近红外光谱分析技术可实现快速、无损检测,用于判别研究孵化早期种鸡蛋受精信息,但现有光谱检测方法未能满足孵化早期受精判别位置要求,亟需构建采集数据时的检测位置与内部信息之间的关系。该研究利用可见/近红外光谱检测系统采集种蛋壳漫反射光谱强度,试验选用壳色相近、表面无裂纹的181个新鲜种鸡蛋,从中随机选择61个样本完成交叉验证。为消除暗电流的影响,进行光谱校正,得出种蛋壳漫反射率,发现受精蛋与未受精蛋的光谱曲线趋势相同,受精蛋和无精蛋赤道处的光谱曲线均高于两端。剔除光谱曲线两端噪声大、信噪比低的波段,选择440.27～874.6 nm作为有效光谱波段,并采用Savitzkg-Golay（S-G）平滑法、二阶导数法Second Derivative、标准正态变量校正SNV、变量标准化Normalization和多元散射校正MSC预处理法分别构建PCA-SVM判别模型。通过对入孵后24,48,72,96和120 h不同位置所采光谱数据,与受精信息综合分析,结果发现二阶导数法Second Derivative和多元散射校正MSC两种预处理方式在同一时间、不同位置的训练集和验证集的判别准确率均相同,说明这两种预处理方法对数据来源位置不敏感;变量标准化Normalization预处理和S-G平滑法预处理验证集的判别准确率则随着时间的推移在一定范围内波动,在种鸡蛋胚胎发育120h时的判别准确率可达91.71%;SNV预处理赤道处验证集判别准确率随着时间的推移呈现上升趋势,对数据来源时间及位置敏感,种鸡蛋胚胎发育越长判别效果越佳,120 h赤道侧的判别准确率为91.16%。且平滑处理、标准正态变量校正和变量标准化三种预处理方式均存在赤道侧判别准确率高于种蛋端部的现象,这主要是由于赤道侧较种鸡蛋两端表面平缓,采集到的信息更多,该研究为早期判别受精蛋与无精蛋的数据采集位置提供新思路和新方法。     

Speckle characteristics of a broad-area VCSEL in the incoherent emission regime

We present a technique to reduce the speckle contrast of a NIR broad-area VCSEL based on the spatially incoherent emission regime that can be obtained when using the proper driving conditions. We evaluate the efficiency of this technique to reduce the speckle contrast by comparing it with the speckle characteristics in multimode emission under cw operation. Depending on the illumination setup, the incoherent emission regime can lead to a strongly reduced speckle contrast down to 1.3%. This is in agreement with estimates of the expected speckle contrast reduction when three contrast reducing effects are taken into account. These low contrast values make the investigated sources attractive for several applications that suffer from speckle noise.     

XYZ particles at Belle

In this paper, I review recent progress in the study of the XYZ particles at Belle. I only focus on studies with charmonium and one or more light mesons in the final states. This covers the X(3872), X(3915),Y(4140), X(4350), and the charged Z states.     

Beyond the LAN: Ethernet’s Evolution into the Public Network

This article details the evolution of Ethernet into Gigabit Ethernet and how this LAN-based technology has undergone major transformations over time. From its data rates and distances to supported media and functionality, Ethernet has greatly improved, enabling it to surmount many of its former limitations and in so doing to expand beyond the LAN into the MAN and now even the WAN. In this article, Pioneer Consulting explores the evolution further by focusing on some of the major technological directions in the Ethernet equipment industry.     

Optical transmission through an interface between subwavelength slits

This paper studies optical transmission through an interface between two slits with different widths in a sheet composed of an ideal conductor. Such a structure is of potential use in fabricating optical diode and may be the simplest one compared to other designs. Our calculations show that there is a critical wavelength. When the light wavelength is below the critical wavelength, the transmissivity is unidirectional. The expression of the stable transmissivity as a function of the ratio of the widths of the two slits was obtained analytically. Particularly, at the critical wavelength, the transmissivities are zero. This phenomenon has great potential for application in the manufacture of wavelength blockers.     

带有碳杂质的钨中氢稳定性的第一性原理研究

应用第一性原理计算方法研究了碳(C)原子对钨(W)中氢(H)原子稳定性的影响. 本征W中, 当C-H间距离为～2.5 Å时, H的溶解能出现最低值, 此时为H最稳定的位置. W中存在空位时, 由于C的影响, H占据的最佳电子密度面值为0.10 Å^-3. 研究发现, W中单空位最多能容纳10个H原子, 且不能形成H分子, 不同于没有C存在的情况, 表明C对W中H稳定性存在很大影响. 此外, 当两个C原子存在于空位中时, H占据的最佳电子密度面值变为0.13 Å^-3.     

Effect of swift heavy ion irradiation on photoluminescence properties of ZnO/PMMA nanocomposite films

We report a study on the SHI induced modifications on structural and optical properties of ZnO/PMMA nanocomposite films. The ZnO nanoparticles were synthesized by the chemical route using 2-mercaptoethanol as a capping agent. The structure of ZnO nanoparticles was confirmed by XRD, SEM and TEM. These ZnO nanoparticles were dispersed in the PMMA matrix to form ZnO/PMMA nanocomposite films by the solution cast method. These ZnO/PMMA nanocomposite films were then irradiated by swift heavy ion irradiation (Ni⁸⁺ ion beam, 100 MeV) at a fluence of 1×10¹¹ ions/cm². The nanocomposite films were then characterized by XRD, UV-vis absorption spectroscopy and photoluminescence spectroscopy. As revealed from the absorption spectra, absorption edge is not changed by the irradiation but the optical absorption is increased. Enhanced green luminescence at about 527 nm and a less intense blue emission peak around 460 nm were observed after irradiation with respect to the pristine ZnO/PMMA nanocomposite film.     

Grain boundary potential and charge density at grain boundaries of chemically prepared thin silver sulfide films

The grain boundary potential and interface state charge density at the grain boundaries of silver sulfide (Ag₂S) thin films prepared by chemical conversion of cadmium sulfide (CdS) films have been determined from the dc resistance of the material and are found to be sensitive to annealing. A reduction in the grain boundary potential and the grain boundary charge density of the film has been noticed when the source CdS film is annealed at different temperatures prior to chemical conversion. The variation in the grain boundary charge density of the grown Ag₂S film with source annealing temperature has been found to be similar to that of thin cadmium sulfide film, reported earlier. An additional low temperature heat treatment of the sample results in an enhancement in the charge density at the grain boundaries. The change in the silver vacancy and/or oxygen and sulfur content of the films as revealed from the energy dispersive spectra of the films suggests possible role of film composition on the grain boundary charge density.     

Reflections from polished single mode fiber ends

Abstract

The performance of a wavelength division multiplexing (WDM) system with optical cross-connects (OXCs) and in the presence of polarization and nonlinear effects was analyzed. We determined the effect of PMD and PDL; nonlinearity such as XPM, SPM, and FWM; and CD on the system performance. We found that the system outage probability is highest at DGD threshold for the respective maximum eye closure (EC). We showed that the allowable DGD depends on the time slot for one bit T, which is the inverse of the network bit rate. Wider T is more immune to large PMD with the EC still maintained at the same level since DGD/T is unchanged. Our analysis also indicated that as DGD increases, BER increases. The BER also increases with increase in PDL and further increases with the presence of XPM, SPM, FWM, and CD.     

The Effects of Polarization and Non-Linearity on the Performance of WDM System with Optical Cross-Connects

The performance of a wavelength division multiplexing (WDM) system with optical cross-connects (OXCs) and in the presence of polarization and nonlinear effects was analyzed. We determined the effect of PMD and PDL; nonlinearity such as XPM, SPM, and FWM; and CD on the system performance. We found that the system outage probability is highest at DGD threshold for the respective maximum eye closure (EC). We showed that the allowable DGD depends on the time slot for one bit T, which is the inverse of the network bit rate. Wider T is more immune to large PMD with the EC still maintained at the same level since DGD/T is unchanged. Our analysis also indicated that as DGD increases, BER increases. The BER also increases with increase in PDL and further increases with the presence of XPM, SPM, FWM, and CD.     

Radial excitation states of η and η′ in the chiral quark model

A chiral quark model is applied to calculate the spectra of pseudoscalar mesons η and η . By analyzing the obtained spectra, we find that the mesons η (2 1 S 0 ), η(4 1 S 0 ), η (3 1 S 0 ) and η (4 1 S 0 ) are the possible candidates of η(1760), X(1835), X(2120) and X(2370). The strong decay widths of these pseudoscalars to all the possible two-body decay channels are calculated within the framework of the 3 P 0 model. Although the total width of η (21S0 ) is compatible with the BES Collaboration’s experimental value for η(1760), the partial decay width to ωω is too small, which is not consistent with the BES result. If X(1835) is interpreted as η(4 1 S 0 ), the total decay width is compatible with the experimental data, and the main decay modes will be πa 0 (980) and πa 0 (1450), which needs to be checked experimentally. The assignment of X(2120) and X(2370) to η (31S0 ) and η (41S0 ) is disfavored in the present calculation because of the incompatibility of the decay widths.