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1.
INTRODUCTION Consumers’ acceptance of fresh or processedapples is the ultimate goal of apple breeders, foodscientists and supermarket managers. Internal qualityassessment has focused on two major objectives:removal of fruit with internal defects and taste selec-tion. Three major parameters including sugar content,acidity and firmness have to be taken into account todetermine the internal quality and the taste of an apple.Near infrared spectroscopy has been used to measureseveral properti… 相似文献
2.
INTRODUCTION Determination of fruit and vegetable quality is very important for both producers and processors. Watermelon as a delicious fruit has been widely ac-cepted in the world and its internal quality is impor-tant for consumers and merchants. The current fa-vorite way for checking a watermelon is to sense sound or vibration by slapping or rapping it. It is time consuming, tedious, and subject to error. Several studies on assessing the quality of watermelon based on its acoustic o… 相似文献
3.
Xia-ping Fu Jian-ping Li Ying Zhou Yi-bin Ying Li-juan Xie Xiao-ying Niu Zhan-ke Yan Hai-yan Yu 《Journal of Zhejiang University. Science. B》2009,10(2):120-125
The near infrared (NIR) spectroscopy technique has been applied in many fields because of its advantages of simple preparation,fast response,and non-destructiveness.We investigated the potential of NIR spectroscopy in diffuse reflectance mode for determining the soluble solid content (SSC) and acidity (pH) of intact loquats.Two cultivars of loquats (Dahongpao and Jiajiaozhong) harvested from two orchards (Tangxi and Chun'an,Zhejiang,China) were used for the measurement of NIR spectra between 800 and 2500 nm.A total of 400 loquats (100 samples of each cultivar from each orchard) were used in this study.Relationships between NIR spectra and SSC and acidity of ioquats were evaluated using partial least square (PLS) method.Spectra preprocessing options included the first and second derivatives,multiple scatter correction (MSC),and the standard normal variate (SNV).Three separate spectral windows identified as full NIR (800-2500 nm),short NIR (800～1100 nm),and long NIR (1100～2500 nm) were studied in factorial combination with the preprocessing options.The models gave relatively good predictions of the SSC of loquats,with root mean square error of prediction (RMSEP) values of 1.21,1.00,0.965,and 1.16 °Brix for Tangxi-Dahongpao,Tangxi-Jiajiaozhong,Chun'an-Dahongpao,and Chun'an-Jiajiaozhong,respectively.The acidity prediction was not satisfactory,with the RMSEP of 0.382,0.194,0.388,and 0.361 for the above four loquats,respectively.The results indicate that NIR diffuse reflectance spectroscopy can be used to predict the SSC and acidity of loquat fruit. 相似文献
4.
INTRODUCTION Recently increasing demands from consumerhave been observed for premium quality fruit witbetter taste at a higher price. Three major parameters determine the internal quality and the tastof apples. These are hardness, sugar content antitratable acidity, which are still determined destructively. Near-infrared spectroscopy (NIRS) habeen used to nondestructively measure internquality in a wide range of fruits and vegetablesuch as onions (Birth et al., 1985), cantaloupe (… 相似文献
5.
To evaluate the potential of FT-NIR spectroscopy and the influence of the distance between the light source/detection probe and the fruit for measuring the sugar content (SC) of Fuji apples, diffuse reflectance spectra were measured in the spectral range from 12500 to 4000 cm(1 at 0 mm, 2 mm, 4 mm and 6 mm distances. Four calibration models at four distances were established between diffused reflectance spectra and sugar content by partial least squares (PLS) analysis. The correlation coefficients (R) of calibrations ranged from 0.982 to 0.997 with SEC values from 0.138 to 0.453 and the SECV values from 0.74 to 1.58. The best model of original spectra at 0 mm distance yielded high correlation determination of 0.918, a SEC of 0.092, and a SEP of 0.773. The results showed that different light/detection probe-fruit distances influence the apple reflective spectra and SC predictions. 相似文献
6.
Application Fourier transform near infrared spectrometer in rapid estimation of soluble solids content of intact citrus fruits 总被引：1，自引：0，他引：1
Lu HS Xu HR Ying YB Fu XP Yu HY Tian HQ 《Journal of Zhejiang University. Science. B》2006,7(10):794-799
INTRODUCTION Soluble solids content (SSC) is a major charac- teristic used for assessing citrus fruit quality. Near-infrared spectroscopy (NIRS) has been used as a rapid and nondestructive technique for determining the soluble solids content of fruit. Kawano et al.(1992) measured sugar content of peaches in the wavelength region of 680~1235 nm. Their experiments indicated good correlation between the NIR spectra and the sugar content (r=0.97, SEP=0.05 °Brix). Slaughter (1995) devel… 相似文献
7.
The use of near infrared (NIR) spectroscopy was proved to be a useful tool for quality analysis of fruits. A bifurcated fiber type NIR spectrometer, with a detection range of 800～2500 nm by lnGaAs detector, was used to evaluate the firmness of peaches. Anisotropy of NIR spectra and firmness of peaches in relation to detecting positions of different parts (including three latitudes and three longitudes) were investigated. Both spectra absorbency and firmness of peach were influenced by longitudes (i,ii, iii) and latitudes (A, B, C). For modeling, two thirds of the samples were used as the calibration set and the remaining one third were used as the validation or prediction set. Partial least square regression (PLSR) models for different longitude and latitude spectra and for the whole fruit show that collecting several NIR spectra from different longitudes and latitudes of a fruit for NIR calibration modeling can improve the modeling performance. In addition, proper spectra pretreatments like scattering correction or derivative also can enhance the modeling performance. The best results obtained in this study were from the holistic model with multiplicative scattering correction (MSC) pretreatment, with correlation coefficient of cross-validation rcv=0.864, root mean square error of cross-validation RMSECV=6.71 N, correlation coefficient of calibration r=0.948, root mean square error of cali-bration RMSEC=4.21 N and root mean square error of prediction RMSEP=5.42 N. The results of this study are useful for further research and application that when applying NIR spectroscopy for objectives with anisotropic differences, spectra and quality indices are necessarily measured from several parts of each object to improve the modeling performance. 相似文献
8.
小波去噪在基于近红外光谱的砂糖橘水分检测的应用 总被引：1，自引：0，他引：1
水分含量是衡量砂糖橘营养品质的重要指标之一,其快速无损检测显得越来越重要。本文基于小波变换的方法,对砂糖橘的500-2500nm区间的漫反射光谱,利用正交小波函数DBn(n=2,3,…10)分别进行2-6五个水平分解和消噪,并比较了不同小波函数和不同分解水平的消噪效果。结果表明,小波消噪有利于消除导数光谱中的噪声,提高建模精度,基于小波函数DB3(分解尺度为3)消噪后的导数光谱建立的PLS模型的预测相关系数为0.8725,预测均方根误差为0.6767。 相似文献
9.
Hui-rong Xu Peng Yu Xia-ping Fu Yi-bin Ying 《Journal of Zhejiang University. Science. B》2009,10(2):126-132
The use of visible-near infrared (NIR) spectroscopy was explored as a tool to discriminate two new tomato plant varieties in China (Zheza205 and Zheza207).In this study,82 top-canopy leaves of Zheza205 and 86 top-canopy leaves of Zheza207 were measured in visible-NIR reflectance mode.Discriminant models were developed using principal component analysis (PCA),discriminant analysis (DA),and discriminant partial least squares (DPLS) regression methods.After outliers detection,the samples were randomly split into two sets,one used as a calibration set (n=82) and the remaining samples as a validation set (n=82).When predicting the variety of the samples in validation set,the classification correctness of the DPLS model after optimizing spectral pretreatment was up to 93%.The DPLS model with raw spectra after multiplicative scatter correction and Savitzky-Golay filter smoothing pretreatments had the best satisfactory calibration and prediction abilities (correlation coefficient of calibration (Rc)=0.920,root mean square errors of calibration=0.196,and root mean square errors of prediction=0.216).The results show that visible-NIR spectroscopy might be a suitable alternative tool to discriminate tomato plant varieties on-site. 相似文献
10.
基于光谱技术的苹果糖度快速无损检测研究 总被引：2，自引：0，他引：2
论文以＂红富士苹果＂为样品,研究可见/近红外光谱技术进行苹果糖度的无损检测方法。选取30个苹果,用漫反射方式获取苹果的光谱曲线,用WAY-2S数字阿贝折射仪测量苹果的糖度,对光谱曲线进行平滑和消除噪声预处理后,用偏最小二乘法（PLS）对糖度建立相应的光谱预测模型。结果表明,糖度的模型稳定性较好,相关系数r达到了0.869,说明可见/近红外光谱技术可以进行苹果糖度的检测。 相似文献
11.
Measurement and analysis of soil nitrogen and organic matter content using near-infrared spectroscopy techniques 总被引：2，自引：0，他引：2
Near infrared reflectance （N1R） spectroscopy is as a rapid, convenient and simple nondestructive technique useful for quantifying several soil properties. This method was used to estimate nitrogen （N） and organic matter （OM） content in a soil of Zhejiang Province, Hangzhou County. A total of 125 soil samples were taken from the field. Ninety-five samples spectra were used during the calibration and cross validation stage. Thirty samples spectra were used to predict N and OM concentration. NIR spectra of these samples were correlated using partial least square regression. The regression coefficients between measured and predicted values of N and OM was 0.92 and 0.93, and SEP （standard error of prediction） were 3.28 and 0.06, respectively, which showed that NIR method had potential to accurately predict these constituents in this soil. The results showed that NIR spectroscopy could be a good tool for precision farming application. 相似文献
12.
To compare mid-infrared(MIR)and near-infrared(NIR)spectroscopies for the determination of the fat and protein contents in milk,the same sample sets with varying concentrations of fat and protein were measured in the MIR range of 3 200-700 cm-1 and NIR range of 9 000-4 000 cm-1.The spectral features in the two regions were analyzed.The MIR spectra of milk were characteristic due to the MIR inherent molecular specificity,whereas the NIR spectra were relatively characterless due to the NIR low selectivity.Partial least squares(PLS)regression models for fat and protein were developed by using both MIR and NIR spectra.MIR data with no pretreatment gave better results than NIR data.The square correlation coefficient(R2)and the root mean square error of prediction(RMSEP)were 0.98 and 0.10 g/dL for fat and 0.97 and 0.11 g/dL for protein.With NIR techniques,satisfactory results were not obtained with raw data.However,NIR data after pretreatment gave similarly good results to the ones using MIR method.This paper indicates that either of the MIR and NIR spectral methods is reliable for the determination of the fat and protein contents. 相似文献
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偏最小二乘法用于阿昔洛韦片的近红外漫反射快速、无损含量测定 总被引：2，自引：0，他引：2
目的:采用偏最小二乘法结合近红外漫反射光谱,建立阿昔洛韦片的快速无损含量测定模型.方法:以阿昔洛韦片为分析对象,用光纤探头测定近红外漫反射光谱.对光谱进行不同预处理方法建模并进行比较,多元校正模型为偏最小二乘法.结果:在11995.5～4246.7cm-1波长范围内采用一阶导数结合矢量归一化对光谱进行预处理,结果最优.定量模型的浓度范围为27%～53%.预示集平均回收率为98.69%,RSD为4.60%,RMSEP为0.0526.结论:近红外漫反射光谱法快速,简便,无损,能够用于阿昔洛韦片含量测定. 相似文献
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校正变换矩阵法用于多组分染色剂的同时测定研究 总被引：1，自引：1，他引：0
将校正变换矩阵法(CTM)与可见分光光度法相结合,对藏红、荧光桃红、曙红三种染色剂进行不经分离同时测定.使用交叉验证法选择主因子数建立了校正模型,预测结果令人满意.在相同条件下,将校正变换矩阵法与偏最小二乘(PLS)回归的结果进行了比较,结果表明两种方法的预测准确性没有显著性差异. 相似文献
15.
司圣柱 《安徽教育学院学报》2006,24(3):50-53
将偏最小二乘法(PLS)与可见分光光度法相结合,对胭脂红、苋菜红、日落黄三种食用色素进行不经分离的同时定量分析。使用交叉验证法选择主成分数建立了校正模型,预测结果令人满意。采用随机抽样方法研究了校正模型中样品集和样本容量对预测能力的影响,结果表明,在文章所研究的体系中,偏最小二乘法的预测能力不因样品集和样本容量的不同而有明显差异,从而说明了文章所用方法具有较大的可靠性和适用性。 相似文献
16.
在波长范围220-370nm,间隔0.2nm,测定了三种硝基甲苯异构体混合物乙醇溶液的吸光度数据,并用偏最小二乘法进行回归分析,结果显示邻硝基甲苯、间硝基甲苯和对硝基甲苯的回收率分别在98.225％-101.19％、100.25％-103.09％和99.547-100.94％之间.从计算结果可以看出,偏最小二乘法具有良好的预测效果,可用于多组分混合物的同时测定. 相似文献
17.
苹果贮藏期果皮内花青苷的抗氧化性研究 总被引：1，自引：0，他引：1
杨金艳 《临沂师范学院学报》2009,31(6):76-80
以红富士苹果为试材,通过测定不同花青苷含量的果实中α-法尼烯及其氧化产物含量和POD活性,对花青苷在果实贮期的抗氧化作用进行了初步研究．结果表明,花青苷能够显著抑制果皮内α-法尼烯的氧化,并减少其氧化产物共轭三烯在果皮内的积累．花青苷含量高的红富士苹果中,POD活性也高;而花青苷含量迅速降低时,POD活性却迅速升高,说明POD有双重作用,苹果贮藏前期对果实的氧化衰老有抑制效应,后期又参与了花青苷的氧化． 相似文献
18.
Pt/Ti bottom electrodes were fabricated on SiO2/Si substrates by magnetron dual-facing-target sputtering system. Lead zirconate titanate(PZT) thin films were deposited on Pt/Ti/ SiO2/Si substrates by radio frequency (RF) magnetron sputtering system. The thickness of PZT thin films which were deposited for 5 h was about 800 nm. XRD spectra show that PZT thin films deposited in Ar ambience and rapid-thermal-annealed for 20 min at 700 ℃ have good crystallization behavior and perovskite structure. AFM micrographs show that mean diameter of crystallites is 70 nm and surface structures of PZT thin films are uniform and dense. Raw mean, root mean square roughness and mean roughness of PZT thin films are 34.357 nm, 2.479 nm and 1.954 nm respectively. As test frequency is 1 kHz, dielectric constant of PZT thin films is 327.6. Electric hysteresis loop shows that coercive field strength, residual polarization strength and spontaneous polarization strength of PZT thin films are 50 kV/cm, 10 μC/cm2 and 13 μC/cm2 respectively. 相似文献
19.
胡煜 《鞍山师范学院学报》2007,9(4):20-24
主要用偏最小二乘(PLS)方法和二次判别分析(QDA)有监督分类的方法来对基因芯片(微阵列)数据进行分析.PLS是一种提取海量的数据有效特征的有效方法,可以获得与原来基因芯片数据更为接近的成分的提取特征的效果.结果表明用PLS方法事先对数据处理可以提高基因芯片数据分析的准确性. 相似文献
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The graded response model can be used to describe test-taking behavior when item responses are classified into ordered categories. In this study, parameter recovery in the graded response model was investigated using the MULTILOG computer program under default conditions. Based on items having five response categories, 36 simulated data sets were generated that varied on true θ distribution, true item discrimination distribution, and calibration sample size. The findings suggest, first, the correlations between the true and estimated parameters were consistently greater than 0.85 with sample sizes of at least 500. Second, the root mean square error differences between true and estimated parameters were comparable with results from binary data parameter recovery studies. Of special note was the finding that the calibration sample size had little influence on the recovery of the true ability parameter but did influence item-parameter recovery. Therefore, it appeared that item-parameter estimation error, due to small calibration samples, did not result in poor person-parameter estimation. It was concluded that at least 500 examinees are needed to achieve an adequate calibration under the graded model. 相似文献