Ze'ev Schmilovitch - Academia.edu (original) (raw)
Papers by Ze'ev Schmilovitch
Journal of Testing and Evaluation, 2001
High intercorrelation between absorbance at different wavelengths is common in near infrared anal... more High intercorrelation between absorbance at different wavelengths is common in near infrared analysis and was observed in an experiment to determine lycopene in tomatoes. Simulation analysis and experiments were conducted to estimate the effects of this problem on the estimators and on the predictive ability of linear regression and ridge regression. Applying linear regression to the experimental data resulted in very large parameter values, implying poor predictive ability. When linear regression gives very large parameter values, the estimated parameters are practically random numbers and are not correlated to the true ones. Ridge regression yielded estimators with normal values, but which are still poorly correlated with the true parameters. However, the predictive ability of the derived equation is good and may be used in practice to determine lycopene content in tomatoes since it is relatively easy to update.
Journal of Analytical Atomic Spectrometry
Generalized multivariate regression for XRF spectra quantifies leaf minerals in multiple crops, b... more Generalized multivariate regression for XRF spectra quantifies leaf minerals in multiple crops, but crop-specific spectral models yield superior results.
Transactions of the ASABE, 2006
FTIR absorbance spectra of four foodborne pathogens suspended in four common food matrices at thr... more FTIR absorbance spectra of four foodborne pathogens suspended in four common food matrices at three different concentrations were used with artificial neural networks (ANNs) for identification and quantification. The classification accuracy of the ANNs was 93.4% for identification and 95.1% for quantification when validated using a subset of the data set. The accuracy of the ANNs when validated for identification of the pathogens studied at four different concentrations using an independent data set had an accuracy range from 60% to 100% and was strongly influenced by background noise. The pathogens could be identified irrespective of the food matrix in which they were suspended, although the classification accuracy was reduced at lower concentrations. More sophisticated background noise filtration techniques are needed to further improve the predictions.
Transactions of the ASAE, 2005
FTIR absorbance spectra in conjunction with artificial neural networks (ANNs) were used to differ... more FTIR absorbance spectra in conjunction with artificial neural networks (ANNs) were used to differentiate selected microorganisms at the generic and serogroup levels. The ANN consisted of three layers with 595 input nodes, 50 nodes at the hidden layer, and 5 output nodes (one for each microorganism or strain). Ten replications of each experiment were conducted, and 70% of the data was used for training and 30% for validation of the network. Results indicated that differentiation could be achieved at an accuracy of 80% to 100% at the generic level and 90% to 100% at the serogroup level at 103 CFU/mL concentration.
Acta Horticulturae, 2001
Mature avocado (Persea americana Mill.) fruit do not ripen on the tree, but soften several days a... more Mature avocado (Persea americana Mill.) fruit do not ripen on the tree, but soften several days after being picked. There are no visible changes in the fruit, which can be used for determining maturity. Acceptable maturity indices for avocado are oil content and dry weight content, but common tests for these are destructive and labor intensive, and are limited in the number of sampled fruits that can be analyzed. A reliable non-destructive test for avocado maturity is required. The feasibility of near-infrared (NIR) spectrometry as a rapid and nondestructive alternative method for the determination of the maturity stage was tested in several orchards during the 1996 season. Several batches of fruits (100 fruits per batch) were scanned individually, in reflectance mode, in the wavelength range, 1200 to 2400 nm. Dry matter content was measured for each fruit. NIR models were developed based on Partial Least Square (PLS) regression with respect to the first derivative of the spectra. NIR models showed prediction accuracy of 0.9-1.3% Standard Error of Prediction (SEP). NIR spectrometry should be considered as an alternative method for maturity determination of avocado.
Transactions of the ASAE, 1992
The physical characteristics of a gaseous fluidized bed and their influence on the bed's apparent... more The physical characteristics of a gaseous fluidized bed and their influence on the bed's apparent density were examined. The effects of air velocity through the bed, air distributor resistance, medium particles size, and the location within the bed were evaluated. Empirical equations were developed in order to relate apparent density average and variance to fluidization parameters using nonlinear regression techniques. The equations indicated correlation coefficients of 0.84 to 0.98 in respect to the experimental data. The results indicate that for each combination of an air distributor and medium, it is possible to find a specific air velocity through the bed, which ensures a constant average apparent density at all depths. KEYWORDS. Separators, Fluidized bed. Density. agricultural products, in which the differences in specific gravity are small (Zaltzman et al., 1987). Many research studies employed the analogy between a fluidized bed and liquid (Zabrodsky, 1966; Kunii and Levenspiel, 1969; Davidson and Harrison, 1971). One proof of such an analogy is that bodies in a fluidized bed obey Archimedes' law. Another manifestation of the analogy is the similarity between the bed layer pressure and the hydrostatic pressure as related to the density and depth. These two expressions of the analogy were used in this work. The objectives of this research were to investigate the apparent density of the FBM and its variations and to develop a method for calculating the effect of the fluidized bed parameters on the apparent density variations. Article has been reviewed and approved for publication by the Power and Machinery Div. of ASAE in October 1991. No. 3265-e, 1991 series. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel.
Transactions of the ASAE, 2005
Bacteria detection methods that are presently used in laboratories and quality control inspection... more Bacteria detection methods that are presently used in laboratories and quality control inspections, such as serological testing, biological enrichment, culturing, and gas chromatograph mass spectroscopy (GCMS), are expensive, labor intensive, and time consuming. Therefore, in order to ensure that consumers receive a safe and high-quality product, rapid and reliable methods need to be developed for detection of pathogens. Raman spectroscopy, an optical technique based on light scattering, was investigated as a means of rapid on-site produce safety assessment. In this study, a dispersive system spectrophotometer, with a 785 nm diode laser, was employed. Chemometric methods such as partial least squares (PLS) regression and classification analysis were used to evaluate low-concentration suspensions of Erwinia carotovora pv. carotovora (ECC) and Clavibacter michiganense (CBM). The pathogens chosen represent Gram-positive and Gram-negative bacteria. A clear distinction between samples containing bacteria and clean samples was obtained by this method. The system was able to determine bacterial concentrations within 2% of the level in the basic bacteria suspension, based on PLS regression models. Classification analysis enables researchers to detect the presence of each of the tested bacteria in mixed-bacteria suspensions that contain between 10 and 100 cells/mL of ECC and CBM.
Transactions of the ASAE, 1983
A new method utilizing a fluidized bed medium for the separation of potatoes from stones and clod... more A new method utilizing a fluidized bed medium for the separation of potatoes from stones and clods was studied and developed. A preliminary study showed that this method is promising. It was found that sand would be a good inexpensive medium for this purpose and the process's parameters were determined. An experimental model for continuous separation was developed and tested. For examination of this method under field conditions, a pilot plant was built and tested. The results of field tests showed that the machine can efficiently separate potatoes from clods and stones.
ABSTRACT VIS-NIR spectroscopy was studied for estimating the minerals: nitrogen (N), phosphorous ... more ABSTRACT VIS-NIR spectroscopy was studied for estimating the minerals: nitrogen (N), phosphorous (P) and potassium (K) in olives leaves as a tool for control fertilization in olive orchards. Olive leaf samples (cv. Barnea) were taken from orchards which were fertilized in a wide range of fertilization levels. Leaf samples were tested in three modes: a. dried grinded leaves; b. fresh grinded leaves; and c. intact leaves. Reflectance measurements were taken using three spectrometers: USB-2000 for VISNIR (450-1000 nm) and LIGA and Luminar-5030 for SWIR (1100-1700 nm). Mineral concentrations of the same samples were measured analytically as reference for spectral analysis. Spectral analysis was conducted by means of Partial Least Square Regression (PLSR). Best prediction model for comprehensive in-season and between season samples (160 samples from 3 seasons, 18 dates) was obtained using LUMINAR spectrometer based on well-grinded dry leaves (R 2 of 0.91). Classification into three N levels was evaluated and obtained an overall accuracy of 0.830 with kappa of 0.745 (substantial). Models for intact leaves analysis yielded non sufficient correlations. The results showed that dehydration improved the model's performances significantly and that VIS-NIR spectroscopy might be used for decision making in fertilizing procedure. Finally a protocol is suggested for laboratory spectral measurements.
Postharvest Biology and Technology, 2012
ABSTRACT The present study created a basis for development of a fast, non-destructive method to m... more ABSTRACT The present study created a basis for development of a fast, non-destructive method to measure ascorbic acid content during various growth stages of three bell pepper cultivars: ‘Ever Green’, ‘No. 117’ and ‘Celica’. Fruit were tagged at the flowering stage and picked weekly during 9 weeks of growth, until fully ripe. Visible and near-infrared (VIS–NIR) spectra in the range 477–950 nm were obtained in reflectance mode from intact peppers with a USB2000 mini-spectrometer. Short-wave infrared (SWIR) spectra in the range 850–1888 nm were obtained in reflectance mode from the same sampled peppers with a Liga Spectrometer. Fruit flesh samples were cut from the area scanned for spectral measurements, and destructively analyzed for ascorbic acid content. The highest ascorbic acid content was measured in the green variety ‘Ever Green’ (148.1 mg per 100 g). Varieties ‘Ever Green’ and ‘No. 117’ accumulated significantly higher concentrations of ascorbic acid than ‘Celica’, and consistent and significant differences were found between the premature, green and mature stages of all three cultivars. Partial Least-Squares (PLS) regression was used in spectral model development. Comparisons were made between the PLS regression analysis of the reflectance spectra (R), its first derivative (D1R), the log(1/R) and its first (D1log(1/R)) and second derivative (D2log(1/R)). VIS–NIR and SWIR spectroscopy measurements showed good correlation (r2 = 0.76) with changes in ascorbic acid content. The PLS regression models were able to predict ascorbic acid content for all three cultivars, with 15.1–18.9 mg per 100 g cross-validation error (RPD = 2–2.4). The method offers potential for non-destructive detection of changes in ascorbic acid content during growth and maturation of intact bell peppers.
Postharvest Biology and Technology, 2013
ABSTRACT A hand-held instrument (DA Meter, Sinteleia, Bolonga, Italy) which measures chlorophyll ... more ABSTRACT A hand-held instrument (DA Meter, Sinteleia, Bolonga, Italy) which measures chlorophyll nondestructively and gives an IAD index (index of the absorption difference between 670 and 720 nm), was used to measure quality attributes of three cultivars of apples. A preharvest study conducted in a ‘Starking’ apple orchard found determination coefficients of r2 values of 0.79 to 0.64 between the IAD index and starch levels, firmness, TSS and TA of fruit. Three orchards of ‘Starking’, ‘Granny Smith’ and ‘Pink Lady’ apples were sampled during commercial harvest and the apples held in air storage for up to six months. The IAD index measured either at harvest or at removal from storage was correlated with TSS, TA and firmness of the apples. The r2 values were best for TSS (0.76) and poorest for firmness (0.51). Moreover, the measurement at harvest and at removal from storage gave similar prediction coefficients for quality attributes. This measurement can be used to sort at harvest for different quality classes after storage, or at removal from storage for different marketing classes.
Journal of Near Infrared Spectroscopy, 2007
Otitis media is one of the most common childhood ailments and, therefore, has a significant impac... more Otitis media is one of the most common childhood ailments and, therefore, has a significant impact on public healthcare expenditure. The initial diagnosis is usually performed by a primary-care physician and is based upon otoscopy and symptomatology; the certainty of diagnosis of acute otitis media is only 58–73%. This study aimed to assess the efficacy of a spectrophotometer-based system in identifying otitis media by comparing the output from the system with the clinical diagnosis of an experienced otologist and, hence, to evaluate the system as a diagnostic aid to primary-care physicians. The study was prospective and double blind. An otologist examined 258 patients consecutively with an oto-microscope and all of the patients were simultaneously examined with a spectrometer-based data acquisition system incorporated in a standard otoscope. The otologist's diagnosis served as a “gold standard”. The acquired data were analysed by means of partial least squares regression. The s...
Biosystems Engineering, 2013
VIS-NIR spectroscopy for estimation of Nitrogen (N) content in olive leaves was studied as a tool... more VIS-NIR spectroscopy for estimation of Nitrogen (N) content in olive leaves was studied as a tool for efficient fertilisation in olive (Olea europaea) orchards. Olive leaf samples (cv. Barnea) were taken from orchards which had been fertilised with a wide range of N levels. Dried ground leaves, fresh ground leaves and intact leaves were tested. Reflectance measurements were taken using three spectrometers: USB-2000 for VIS-NIR (450 e1000 nm) and a LIGA, and a Luminar-5030 for SWIR (1100e1700 nm). Nitrogen concentrations of the same samples were measured analytically as a reference for the spectral analyses, which were conducted by means of partial least square regression (PLSR). The best predictive model for comprehensive in-season and between-season samples (160 samples from three seasons, taken on 18 separate days) was obtained using the Luminar spectrometer using thoroughly ground dried leaves (R 2 ¼ 0.91). Classification into three N levels was evaluated and gave an overall accuracy of 0.83 with a kappa of 0.75 (substantial). Intact leaves yielded non-sufficient correlations. The results showed that leaf dehydration improves the model performance significantly and that VIS-NIR spectroscopy might be used for decision-making in fertilisation procedures. Finally, a protocol is suggested for laboratory spectral measurements.
Biosystems Engineering, 2013
ABSTRACT The objective of the present study was to develop a fast, non-destructive method to meas... more ABSTRACT The objective of the present study was to develop a fast, non-destructive method to measure the bell pepper chlorophyll content, which is one of the major maturity indices for determining harvesting time. The research is based on visible-near-infrared (VIS-NIR) and short-wave infrared (SWIR) spectrometry. Red, green and yellow varieties were examined: 'Celica', 'Ever Green' and 'No.117', respectively. Peppers were marked at the flowering stage, and 20 samples of each variety were collected weekly during nine weeks until full growth. Disc samples of the fruit flesh were analysed destructively, the spectrometry data were analysed chemometrically, and a nonlinear-kernel algorithm was developed for spectral data analysis. Comparisons were made between the linear and nonlinear regression analyses of the raw reflectance spectra (R), on one hand, and the preprocessed spectra such as the first derivative of R (D1R), log(1/R), D-1(log(1/R)) and D-2(log(1/R)), on the other hand. For further evaluation of the regression models a standardised weighted sum (SWS) index was developed, based on criterion weighting. The developed kernel algorithm, partial least squares (PLSR), and support vector machine (SVM) regression models were able to predict total chlorophyll and carotenoid contents for all three tested bell pepper cultivars, with average cross-validation errors of 0.007 and 0.01 mg g(-1), respectively. The kernel nonlinear analysis of the spectral data yielded the most promising regression models for all three cultivars.
Journal of Agricultural Engineering Research, 1981
A new version of a gravity separator was developed to facilitate separation of large quantities o... more A new version of a gravity separator was developed to facilitate separation of large quantities of clods and stones from peanuts in the field. Separation takes place over an inclined mesh belt conveyor. Air passing through the conveyor lifts the lighter particles above the surface and they then flow downhill by gravity. The heavier particles remain in contact with the conveyor and move uphill. Mechanical vibrations used on conventional gravity separators as a means of conveying and agitating the material were eliminated to make the unit more suitable for use in the field. The unit is self-cleaning and cannot be blocked by vegetation debris from the field. The effect of the parameters was investigated for various mixtures of peanuts and clods and the relation between the slope and velocity of the mesh conveyor was determined. Field tests showed that the unit can separate mixtures containing a large percentage of clods (up to 99 %) at a high pour rate. Therefore, it should be suitable for peanut-salvaging machines operating in medium or heavy soils. The unit also separates clods and stones from almonds in their green hulls.
Journal of Agricultural Engineering Research, 1986
ABSTRACT
Journal of Quantitative Spectroscopy and Radiative Transfer, 2001
A method to overcome multicollinearity, based on deduction of the stochastic disturbance from the... more A method to overcome multicollinearity, based on deduction of the stochastic disturbance from the dependent variable, was developed. This method resulted in a marked increase in the coe$cient of determination * R associated with the`corrected dependent variablea. Simulation results revealed that the proposed method yielded good estimation of those stochastic disturbance. The resulting`correcteda dependent variable may be incorporated into some of the existing methods for overcoming multicollinearity. Application of least-squares regression to the`correcteda dependent variable yields estimators of normal size, and the predictive ability of the derived equation is excellent.
Innovation in Agricultural Robotics for Precision Agriculture, 2021
Journal of Testing and Evaluation, 2001
High intercorrelation between absorbance at different wavelengths is common in near infrared anal... more High intercorrelation between absorbance at different wavelengths is common in near infrared analysis and was observed in an experiment to determine lycopene in tomatoes. Simulation analysis and experiments were conducted to estimate the effects of this problem on the estimators and on the predictive ability of linear regression and ridge regression. Applying linear regression to the experimental data resulted in very large parameter values, implying poor predictive ability. When linear regression gives very large parameter values, the estimated parameters are practically random numbers and are not correlated to the true ones. Ridge regression yielded estimators with normal values, but which are still poorly correlated with the true parameters. However, the predictive ability of the derived equation is good and may be used in practice to determine lycopene content in tomatoes since it is relatively easy to update.
Journal of Analytical Atomic Spectrometry
Generalized multivariate regression for XRF spectra quantifies leaf minerals in multiple crops, b... more Generalized multivariate regression for XRF spectra quantifies leaf minerals in multiple crops, but crop-specific spectral models yield superior results.
Transactions of the ASABE, 2006
FTIR absorbance spectra of four foodborne pathogens suspended in four common food matrices at thr... more FTIR absorbance spectra of four foodborne pathogens suspended in four common food matrices at three different concentrations were used with artificial neural networks (ANNs) for identification and quantification. The classification accuracy of the ANNs was 93.4% for identification and 95.1% for quantification when validated using a subset of the data set. The accuracy of the ANNs when validated for identification of the pathogens studied at four different concentrations using an independent data set had an accuracy range from 60% to 100% and was strongly influenced by background noise. The pathogens could be identified irrespective of the food matrix in which they were suspended, although the classification accuracy was reduced at lower concentrations. More sophisticated background noise filtration techniques are needed to further improve the predictions.
Transactions of the ASAE, 2005
FTIR absorbance spectra in conjunction with artificial neural networks (ANNs) were used to differ... more FTIR absorbance spectra in conjunction with artificial neural networks (ANNs) were used to differentiate selected microorganisms at the generic and serogroup levels. The ANN consisted of three layers with 595 input nodes, 50 nodes at the hidden layer, and 5 output nodes (one for each microorganism or strain). Ten replications of each experiment were conducted, and 70% of the data was used for training and 30% for validation of the network. Results indicated that differentiation could be achieved at an accuracy of 80% to 100% at the generic level and 90% to 100% at the serogroup level at 103 CFU/mL concentration.
Acta Horticulturae, 2001
Mature avocado (Persea americana Mill.) fruit do not ripen on the tree, but soften several days a... more Mature avocado (Persea americana Mill.) fruit do not ripen on the tree, but soften several days after being picked. There are no visible changes in the fruit, which can be used for determining maturity. Acceptable maturity indices for avocado are oil content and dry weight content, but common tests for these are destructive and labor intensive, and are limited in the number of sampled fruits that can be analyzed. A reliable non-destructive test for avocado maturity is required. The feasibility of near-infrared (NIR) spectrometry as a rapid and nondestructive alternative method for the determination of the maturity stage was tested in several orchards during the 1996 season. Several batches of fruits (100 fruits per batch) were scanned individually, in reflectance mode, in the wavelength range, 1200 to 2400 nm. Dry matter content was measured for each fruit. NIR models were developed based on Partial Least Square (PLS) regression with respect to the first derivative of the spectra. NIR models showed prediction accuracy of 0.9-1.3% Standard Error of Prediction (SEP). NIR spectrometry should be considered as an alternative method for maturity determination of avocado.
Transactions of the ASAE, 1992
The physical characteristics of a gaseous fluidized bed and their influence on the bed's apparent... more The physical characteristics of a gaseous fluidized bed and their influence on the bed's apparent density were examined. The effects of air velocity through the bed, air distributor resistance, medium particles size, and the location within the bed were evaluated. Empirical equations were developed in order to relate apparent density average and variance to fluidization parameters using nonlinear regression techniques. The equations indicated correlation coefficients of 0.84 to 0.98 in respect to the experimental data. The results indicate that for each combination of an air distributor and medium, it is possible to find a specific air velocity through the bed, which ensures a constant average apparent density at all depths. KEYWORDS. Separators, Fluidized bed. Density. agricultural products, in which the differences in specific gravity are small (Zaltzman et al., 1987). Many research studies employed the analogy between a fluidized bed and liquid (Zabrodsky, 1966; Kunii and Levenspiel, 1969; Davidson and Harrison, 1971). One proof of such an analogy is that bodies in a fluidized bed obey Archimedes' law. Another manifestation of the analogy is the similarity between the bed layer pressure and the hydrostatic pressure as related to the density and depth. These two expressions of the analogy were used in this work. The objectives of this research were to investigate the apparent density of the FBM and its variations and to develop a method for calculating the effect of the fluidized bed parameters on the apparent density variations. Article has been reviewed and approved for publication by the Power and Machinery Div. of ASAE in October 1991. No. 3265-e, 1991 series. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel.
Transactions of the ASAE, 2005
Bacteria detection methods that are presently used in laboratories and quality control inspection... more Bacteria detection methods that are presently used in laboratories and quality control inspections, such as serological testing, biological enrichment, culturing, and gas chromatograph mass spectroscopy (GCMS), are expensive, labor intensive, and time consuming. Therefore, in order to ensure that consumers receive a safe and high-quality product, rapid and reliable methods need to be developed for detection of pathogens. Raman spectroscopy, an optical technique based on light scattering, was investigated as a means of rapid on-site produce safety assessment. In this study, a dispersive system spectrophotometer, with a 785 nm diode laser, was employed. Chemometric methods such as partial least squares (PLS) regression and classification analysis were used to evaluate low-concentration suspensions of Erwinia carotovora pv. carotovora (ECC) and Clavibacter michiganense (CBM). The pathogens chosen represent Gram-positive and Gram-negative bacteria. A clear distinction between samples containing bacteria and clean samples was obtained by this method. The system was able to determine bacterial concentrations within 2% of the level in the basic bacteria suspension, based on PLS regression models. Classification analysis enables researchers to detect the presence of each of the tested bacteria in mixed-bacteria suspensions that contain between 10 and 100 cells/mL of ECC and CBM.
Transactions of the ASAE, 1983
A new method utilizing a fluidized bed medium for the separation of potatoes from stones and clod... more A new method utilizing a fluidized bed medium for the separation of potatoes from stones and clods was studied and developed. A preliminary study showed that this method is promising. It was found that sand would be a good inexpensive medium for this purpose and the process's parameters were determined. An experimental model for continuous separation was developed and tested. For examination of this method under field conditions, a pilot plant was built and tested. The results of field tests showed that the machine can efficiently separate potatoes from clods and stones.
ABSTRACT VIS-NIR spectroscopy was studied for estimating the minerals: nitrogen (N), phosphorous ... more ABSTRACT VIS-NIR spectroscopy was studied for estimating the minerals: nitrogen (N), phosphorous (P) and potassium (K) in olives leaves as a tool for control fertilization in olive orchards. Olive leaf samples (cv. Barnea) were taken from orchards which were fertilized in a wide range of fertilization levels. Leaf samples were tested in three modes: a. dried grinded leaves; b. fresh grinded leaves; and c. intact leaves. Reflectance measurements were taken using three spectrometers: USB-2000 for VISNIR (450-1000 nm) and LIGA and Luminar-5030 for SWIR (1100-1700 nm). Mineral concentrations of the same samples were measured analytically as reference for spectral analysis. Spectral analysis was conducted by means of Partial Least Square Regression (PLSR). Best prediction model for comprehensive in-season and between season samples (160 samples from 3 seasons, 18 dates) was obtained using LUMINAR spectrometer based on well-grinded dry leaves (R 2 of 0.91). Classification into three N levels was evaluated and obtained an overall accuracy of 0.830 with kappa of 0.745 (substantial). Models for intact leaves analysis yielded non sufficient correlations. The results showed that dehydration improved the model's performances significantly and that VIS-NIR spectroscopy might be used for decision making in fertilizing procedure. Finally a protocol is suggested for laboratory spectral measurements.
Postharvest Biology and Technology, 2012
ABSTRACT The present study created a basis for development of a fast, non-destructive method to m... more ABSTRACT The present study created a basis for development of a fast, non-destructive method to measure ascorbic acid content during various growth stages of three bell pepper cultivars: ‘Ever Green’, ‘No. 117’ and ‘Celica’. Fruit were tagged at the flowering stage and picked weekly during 9 weeks of growth, until fully ripe. Visible and near-infrared (VIS–NIR) spectra in the range 477–950 nm were obtained in reflectance mode from intact peppers with a USB2000 mini-spectrometer. Short-wave infrared (SWIR) spectra in the range 850–1888 nm were obtained in reflectance mode from the same sampled peppers with a Liga Spectrometer. Fruit flesh samples were cut from the area scanned for spectral measurements, and destructively analyzed for ascorbic acid content. The highest ascorbic acid content was measured in the green variety ‘Ever Green’ (148.1 mg per 100 g). Varieties ‘Ever Green’ and ‘No. 117’ accumulated significantly higher concentrations of ascorbic acid than ‘Celica’, and consistent and significant differences were found between the premature, green and mature stages of all three cultivars. Partial Least-Squares (PLS) regression was used in spectral model development. Comparisons were made between the PLS regression analysis of the reflectance spectra (R), its first derivative (D1R), the log(1/R) and its first (D1log(1/R)) and second derivative (D2log(1/R)). VIS–NIR and SWIR spectroscopy measurements showed good correlation (r2 = 0.76) with changes in ascorbic acid content. The PLS regression models were able to predict ascorbic acid content for all three cultivars, with 15.1–18.9 mg per 100 g cross-validation error (RPD = 2–2.4). The method offers potential for non-destructive detection of changes in ascorbic acid content during growth and maturation of intact bell peppers.
Postharvest Biology and Technology, 2013
ABSTRACT A hand-held instrument (DA Meter, Sinteleia, Bolonga, Italy) which measures chlorophyll ... more ABSTRACT A hand-held instrument (DA Meter, Sinteleia, Bolonga, Italy) which measures chlorophyll nondestructively and gives an IAD index (index of the absorption difference between 670 and 720 nm), was used to measure quality attributes of three cultivars of apples. A preharvest study conducted in a ‘Starking’ apple orchard found determination coefficients of r2 values of 0.79 to 0.64 between the IAD index and starch levels, firmness, TSS and TA of fruit. Three orchards of ‘Starking’, ‘Granny Smith’ and ‘Pink Lady’ apples were sampled during commercial harvest and the apples held in air storage for up to six months. The IAD index measured either at harvest or at removal from storage was correlated with TSS, TA and firmness of the apples. The r2 values were best for TSS (0.76) and poorest for firmness (0.51). Moreover, the measurement at harvest and at removal from storage gave similar prediction coefficients for quality attributes. This measurement can be used to sort at harvest for different quality classes after storage, or at removal from storage for different marketing classes.
Journal of Near Infrared Spectroscopy, 2007
Otitis media is one of the most common childhood ailments and, therefore, has a significant impac... more Otitis media is one of the most common childhood ailments and, therefore, has a significant impact on public healthcare expenditure. The initial diagnosis is usually performed by a primary-care physician and is based upon otoscopy and symptomatology; the certainty of diagnosis of acute otitis media is only 58–73%. This study aimed to assess the efficacy of a spectrophotometer-based system in identifying otitis media by comparing the output from the system with the clinical diagnosis of an experienced otologist and, hence, to evaluate the system as a diagnostic aid to primary-care physicians. The study was prospective and double blind. An otologist examined 258 patients consecutively with an oto-microscope and all of the patients were simultaneously examined with a spectrometer-based data acquisition system incorporated in a standard otoscope. The otologist's diagnosis served as a “gold standard”. The acquired data were analysed by means of partial least squares regression. The s...
Biosystems Engineering, 2013
VIS-NIR spectroscopy for estimation of Nitrogen (N) content in olive leaves was studied as a tool... more VIS-NIR spectroscopy for estimation of Nitrogen (N) content in olive leaves was studied as a tool for efficient fertilisation in olive (Olea europaea) orchards. Olive leaf samples (cv. Barnea) were taken from orchards which had been fertilised with a wide range of N levels. Dried ground leaves, fresh ground leaves and intact leaves were tested. Reflectance measurements were taken using three spectrometers: USB-2000 for VIS-NIR (450 e1000 nm) and a LIGA, and a Luminar-5030 for SWIR (1100e1700 nm). Nitrogen concentrations of the same samples were measured analytically as a reference for the spectral analyses, which were conducted by means of partial least square regression (PLSR). The best predictive model for comprehensive in-season and between-season samples (160 samples from three seasons, taken on 18 separate days) was obtained using the Luminar spectrometer using thoroughly ground dried leaves (R 2 ¼ 0.91). Classification into three N levels was evaluated and gave an overall accuracy of 0.83 with a kappa of 0.75 (substantial). Intact leaves yielded non-sufficient correlations. The results showed that leaf dehydration improves the model performance significantly and that VIS-NIR spectroscopy might be used for decision-making in fertilisation procedures. Finally, a protocol is suggested for laboratory spectral measurements.
Biosystems Engineering, 2013
ABSTRACT The objective of the present study was to develop a fast, non-destructive method to meas... more ABSTRACT The objective of the present study was to develop a fast, non-destructive method to measure the bell pepper chlorophyll content, which is one of the major maturity indices for determining harvesting time. The research is based on visible-near-infrared (VIS-NIR) and short-wave infrared (SWIR) spectrometry. Red, green and yellow varieties were examined: 'Celica', 'Ever Green' and 'No.117', respectively. Peppers were marked at the flowering stage, and 20 samples of each variety were collected weekly during nine weeks until full growth. Disc samples of the fruit flesh were analysed destructively, the spectrometry data were analysed chemometrically, and a nonlinear-kernel algorithm was developed for spectral data analysis. Comparisons were made between the linear and nonlinear regression analyses of the raw reflectance spectra (R), on one hand, and the preprocessed spectra such as the first derivative of R (D1R), log(1/R), D-1(log(1/R)) and D-2(log(1/R)), on the other hand. For further evaluation of the regression models a standardised weighted sum (SWS) index was developed, based on criterion weighting. The developed kernel algorithm, partial least squares (PLSR), and support vector machine (SVM) regression models were able to predict total chlorophyll and carotenoid contents for all three tested bell pepper cultivars, with average cross-validation errors of 0.007 and 0.01 mg g(-1), respectively. The kernel nonlinear analysis of the spectral data yielded the most promising regression models for all three cultivars.
Journal of Agricultural Engineering Research, 1981
A new version of a gravity separator was developed to facilitate separation of large quantities o... more A new version of a gravity separator was developed to facilitate separation of large quantities of clods and stones from peanuts in the field. Separation takes place over an inclined mesh belt conveyor. Air passing through the conveyor lifts the lighter particles above the surface and they then flow downhill by gravity. The heavier particles remain in contact with the conveyor and move uphill. Mechanical vibrations used on conventional gravity separators as a means of conveying and agitating the material were eliminated to make the unit more suitable for use in the field. The unit is self-cleaning and cannot be blocked by vegetation debris from the field. The effect of the parameters was investigated for various mixtures of peanuts and clods and the relation between the slope and velocity of the mesh conveyor was determined. Field tests showed that the unit can separate mixtures containing a large percentage of clods (up to 99 %) at a high pour rate. Therefore, it should be suitable for peanut-salvaging machines operating in medium or heavy soils. The unit also separates clods and stones from almonds in their green hulls.
Journal of Agricultural Engineering Research, 1986
ABSTRACT
Journal of Quantitative Spectroscopy and Radiative Transfer, 2001
A method to overcome multicollinearity, based on deduction of the stochastic disturbance from the... more A method to overcome multicollinearity, based on deduction of the stochastic disturbance from the dependent variable, was developed. This method resulted in a marked increase in the coe$cient of determination * R associated with the`corrected dependent variablea. Simulation results revealed that the proposed method yielded good estimation of those stochastic disturbance. The resulting`correcteda dependent variable may be incorporated into some of the existing methods for overcoming multicollinearity. Application of least-squares regression to the`correcteda dependent variable yields estimators of normal size, and the predictive ability of the derived equation is excellent.
Innovation in Agricultural Robotics for Precision Agriculture, 2021