Image Processing
M. Nadafzadeh; A. Banakar; S. Abdanan Mehdizadeh; M. R. Zare-Bavani; S. Minaei
Abstract
IntroductionNowadays, machine vision systems are extensively used in agriculture. The application of this technology in the field can help preserve agricultural resources while reducing manual labor and production costs. In the field of agricultural automation, accurately detecting crop rows is recognized ...
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IntroductionNowadays, machine vision systems are extensively used in agriculture. The application of this technology in the field can help preserve agricultural resources while reducing manual labor and production costs. In the field of agricultural automation, accurately detecting crop rows is recognized as a crucial and challenging issue for weed identification and the automatic guidance of machines. Therefore, it is necessary to explore practical solutions to optimize this process. Hence, the purpose of this study is the precise identification of basil cultivation rows to enable the automatic navigation of robots in the cultivation field.Materials and MethodsIn the first stage of this research, six images from each growth period of basil plants (third, fourth, and fifth week) were taken and weeds were removed from the area between the crop rows using three different methods of area opening, dimensional removal, and masking. In the next stage, six images of crop rows without weeds were examined by performing image processing operations and implementing several routing algorithms, namely, Hough transform, wavelet transform, Gabor filter, linear regression, and an additional algorithm proposed in this study. The output of each of these algorithms was compared with the ideal path identified by the user. For this purpose, after capturing an image, green areas were extracted from it by performing the segmentation process. By applying each of the routing algorithms to the image, plant cultivation lines were identified and their equations were determined. Finally, the performance of the designed robot was evaluated using the most appropriate routing algorithm.Results and DiscussionExamining the performance of three different methods of weed removal in three periods of plant growth (third, fourth, and fifth week) showed that during this interval, the masking method had the lowest error rate compared to the ideal path and the shortest average operation time of 1.64 seconds, followed by the dimensional removal and the area opening methods. Comparing the routes detected by different routing algorithms with the ideal routes and according to the results of the t-test at 5% probability level, the order of the studied routing methods from the most superior is as follows: the proposed algorithm, Gabor filter, linear regression, Hough transform and wavelet transform algorithm. Overall, the proposed algorithm had the highest rate of adaptation to the ideal path (with an average error of 3.65 pixels) and the shortest operation time (4.79 seconds) and was selected as the most appropriate routing algorithm and the performance of the designed robot was evaluated using it.ConclusionA reliable crop row detection algorithm can reduce production costs and preserve the environment. In this study, the masking method was used for removing weeds from the images. The new proposed routing algorithm has superior performance when compared with common routing algorithms such as the Gabor filter, linear regression, Hough transform, and wavelet transform. Additionally, it was shown that the designed robot using the proposed algorithm (with an average error of 3.65 pixels) has the desired performance.AcknowledgmentThe authors express appreciation for the financial support provided by Tarbiat Modares University.
A. Kohan; S. Minaei
Abstract
Several histogram equalization methods for enhancing the color images of Rosa Damascena flowers and some thresholding methods for segmentation of the flowers were examined. Images were taken outdoors at different times of day and light conditions. A factorial experiment in the form of a Completely Randomized ...
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Several histogram equalization methods for enhancing the color images of Rosa Damascena flowers and some thresholding methods for segmentation of the flowers were examined. Images were taken outdoors at different times of day and light conditions. A factorial experiment in the form of a Completely Randomized Design with two factors of histogram equalization method at 8 levels and thresholding method at 15 levels, was implemented. Histogram equalization methods included: CHE, BBHE, BHEPL-D, DQHEPL, DSIHE, RMSHE, RSIHE, and no histogram equalization (NHE) as the control. Thresholding method levels were: Huang, Intermodes, Isodata, Li, maximum entropy, mean, minimum, moments, Otsu, percentile, Renyi’s entropy, Shanbhag, Yen, constant, and global basic thresholding method. The effect of these factors on the properties of the segmented images such as the Percentage of Incorrectly Segmented Area (PISA), Percentage of Overlapping Area (POA), Percentage of Undetected Area (PUA), and Percentage of Detected Flowers (PDF) was investigated. Results of histogram equalization analysis showed that DQHEPL and NHE have the statistically significant lowest PUA (11.13% and 8.32%, respectively), highest POA (89.35% and 92.07%, respectively), and highest PDF (61.88% and 64.94%, respectively). Thresholding methods had a significant effect on PISA, PUA, POA, and PDF. The highest PDF belonged to constant, minimum, and Intermodes (75.07%, 73.08% and 74.30%, respectively) They also had the lowest PISA (0.35%, 1.29%, and 1.85%, respectively) and PUA (33.72%, 23.09%, and 15.56%, respectively). These methods had the highest POA (80.73%, 76.70%, and 84.67%, respectively). Hence, they are suitable methods for segmentation of Rosa Damascena flowers in color images.
B. Jamshidi; A. Arefi; S. Minaei
Abstract
Introduction In recent years, the determination of firmness as an important quality attribute of apple fruits has been widely noticed. Common methods for firmness measurement are destructive and cannot be applied in sorting lines. Therefore, development of a non-destructive, simple, fast, and the low-cost ...
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Introduction In recent years, the determination of firmness as an important quality attribute of apple fruits has been widely noticed. Common methods for firmness measurement are destructive and cannot be applied in sorting lines. Therefore, development of a non-destructive, simple, fast, and the low-cost determination technique of firmness is imperative. Dynamic speckle patterns (DSP) or bio speckle imaging as a new optical technique has been recently noticed for non-destructive quality assessment of food and agricultural products. In this research, the feasibility of using this technique was investigated for non-destructive prediction of firmness in intact apples during five months of cold storage. Materials and Methods During the harvest season, in 2013, a total of 540 ‘Red Delicious’ apples were obtained from a local orchard in Oshnaviyeh, Iran. The apples with similar color and shape were collected from several trees in the same place. The samples were stored under cold conditions for five months. Five experiments were carried out; the first experiment was done immediately after harvesting and other tests were performed during storage time, i.e. 30, 60, 120, and 150 days after harvesting date. In each experiment, the samples were illuminated by two laser diodes at the wavelengths of 680 nm and 780 nm, separately. DSP images of each fruit were acquired using a CCD camera. Then, time history of the speckle pattern (THSP) was created for each sample. After taking images, reference measurements were carried out for each sample to determine its firmness. Quantification of DSP activity was done using the statistical features of inertia moment (IM) and the absolute value of differences (AVD) extracted from the THSP images. Moreover, features of the images were extracted based on texture and wavelet transform. Finally, artificial neural network (ANN) models were developed for prediction of apple firmness based on image’s information obtained from the wavelengths of 680 nm and 780 nm, and the reference measurements. The 60, 15, and 25 percent of total samples were randomly used for calibration, cross-validation, and test validation sets, respectively. The correlation coefficient between measured and predicted values of the firmness and also the standard error of prediction (SEP) were calculated to compare the performance of the different ANN models. Results and Discussion After one month of the storage, apples lost about 15 percent of their initial firmness.The softening process continued and the firmness index dropped to 48.05 N (a total decrease of 42%). A significant difference was observed among the mean values of the firmness belong to the different storage times. In first and second months of the storage, a negative linear relationship was observed between DSP activity and the firmness. The lowest value of IM was observed for apples belonged to the harvesting date. DSP activity suddenly increased after 30 days of the storage. This ascending trend continued and reached to its maximum value on the 60th days of the storage. It was noted that DSP activity is significantly affected by the chlorophyll absorption during this period. Moreover, DSP activity at the wavelength of 680 nm was more than that at 780 nm. After two months of the storage, a significant decrease in DSP activity was observed for both wavelengths of 680 nm and 780 nm. The main reason for this phenomenon came back to changes in carbohydrates. During this ripping period, starch, which plays a main role in backscattering phenomenon is converted into simpler carbohydrates and it causes an increase in soluble solid contents and a decrease in the number of scattering centers. After developing the ANN models, the correlation coefficient of the prediction (rp) for different topologies was ranged from 0.74-0.81 and 0.81-0.83 for the wavelengths of 680 nm and 780 nm, respectively. Moreover, standard error of prediction (SEP) was between 8.4-9 N and 8.1-8.7 N for the wavelengths of 680 nm and 780 nm, respectively. The achieved results may be more attractive when they are compared with obtained results using multispectral/hyperspectral scattering imaging, as expensive and rather complicate techniques for non-destructive firmness assessment in apple fruits. Conclusion It was concluded that dynamic speckle patterns (DSP) or bio speckle imaging could be a simple, low-cost and appropriate technique for non-destructive prediction of firmness in intact apples during storage.
B. Hosseinzdeh Samani; M. H. Khoshtaghaza; S. Minaei; Z. Hamidi Esfahani; M. Tavakloli Dakhrabadi
Abstract
Introduction: The common method used for juice pasteurization is the thermal method since thermal methods contribute highly to inactivating microbes. However, applying high temperatures would lead to inefficient effects on nutrition and food value. Such effects may include vitamin loss, nutritional flavor ...
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Introduction: The common method used for juice pasteurization is the thermal method since thermal methods contribute highly to inactivating microbes. However, applying high temperatures would lead to inefficient effects on nutrition and food value. Such effects may include vitamin loss, nutritional flavor loss, non-enzyme browning, and protein reshaping (Kuldiloke, 2002). In order to decrease the adverse effects of the thermal pasteurization method, other methods capable of inactivation of microorganisms can be applied. In doing so, non-thermal methods including pasteurization using high hydrostatic pressure processing (HPP), electrical fields, and ultrasound waves are of interest (Chen and Tseng, 1996). The reason for diminishing microbial count in the presence of ultrasonic waves could be due to the burst of very tiny bubbles developed by ultrasounds which expand quickly and burst in a short time. Due to this burst, special temperature and pressure conditions are developed which could initiate or intensify several physical and/or chemical reactions. The aim of this study is to evaluate the non-thermal ultrasonic method and its effective factors on the E.coli bacteria of sour cherry.
Materials and methods: In order to supply uniform ultrasonic waves, a 1000 W electric generator (Model MPI, Switzerland) working at 20±1 kHz frequency was used. The aim of this study is to evaluate the non-thermal ultrasonic method and its effective factors on the E.coli bacteria of sour cherry. For this purpose, a certain amount of sour cherry fruit was purchased from local markets. First, the fruits were washed, cleaned and cored. The prepared fruits were then dewatered using an electric juicer. In order to separate pulp suspensions and tissue components, the extracted juice was poured into a centrifuge with the speed of 6000 rpm for 20 min. For complete separation of the remaining suspended particles, the transparent portion of the extract was passed through a Whatman filter paper using a vacuum pump (Mehmandoost et al., 2011). Afterwards, the samples were poured into a reactor with diameter and height of 80 and 50 mm, respectively. It is necessary to mention that the dimensions of the reactor were optimized during pretests.
Probe design: One of the most common types of horns used for ultrasonic machining technologies is step type horn (Naď, 2010). For obtaining the governing equations on deformation along the step type horn in steady state conditions, Eq. (1) was used. In the solution of the mentioned differential equation, the answers are divided into two subsets and each of the answers is obtained considering the boundary conditions (Hosseinzadeh et al., 2013):
(1) c^2.[(∂S/∂x)/(S(x)).(∂u(x,t))/∂x+(∂^2 u(x,t))/〖∂x〗^2 ]=(∂^2 u(x,t))/〖∂t〗^2
From Eq. (1), it can be concluded that:
(2) u(x,t)=(A cos〖ωx/c〗+B sin〖ωx/c)(C cos〖ωt+D sinωt 〗 〗)
The boundary conditions for Eq. (2) are written as follows:
(3) {■(a) (∂u(x))/∂x=0,x=0@b) (∂u(x))/∂x=0,x=l@c) u(0)=u_in )}
One of the most important parts in probe design is preventing stress concentration in locations in which the area changes. To avoid this problem, the displacement in this section must be equal to zero (Hosseinzadeh et al., 2013). For obtaining the probe length, the displacement equation and the l1 parameter are used:
σ=-E.u_in.ω/c.sin〖(ω.x)/c〗 (4)
In order to determine the maximum axial stress in step type probe, Eq. (3) and (4) are derived and set equal to zero. Therefore, the maximum stress will be equal to:
σ_max=π.E.u_in/l (5)
Optimization and Modeling using Response Surface Method: Response surface methodology (RSM) has an important application in the design, development and formulation of new products, as well as in the improvement of existing product designs. It defines the effect of the independent variables, alone or in combination, on processes. In addition, to analyzing the effects of the independent variables, this experimental methodology generates a mathematical model which describes the chemical or biochemical processes (Anjum et al., 1997, Halim et al., 2009).
In order to obtain the optimum value, Eq. (1) will be used:
(6) Y_i=β_0+∑▒〖β_i X_i+∑▒〖β_ij X_i X_j+〗〗 ∑▒〖β_ij X_i^2 〗+ε
where, β0, βj, βij, βjj are regression coefficients for intercept, linear, interaction and quadratic coefficients, respectively, while Xi and Xj are coded independent variables and ε is the error.
For this purpose, four factors of ultrasonic power (200 to 600 W), wave exposure time (5 to 15 min), probe diameter (20 to 40 mm), and probe penetration depth in sour cherry juice container (0 to 40 mm) were selected. First, the probes with the desired diameters were designed using the related formulas by using CAD-CAM.
Results and Discussion: Surface Method (RSM) indicated that the quadratic model with 0.96 coefficient of friction, standard error of 1545.3, and coefficient of variation of 14% is the best model for estimating the number of E.coli bacteria among the different studied treatments. The results showed that with increasing probe diameter and probe depth, the destructive effects of ultrasonic wave increase. It was also revealed that as the probe diameter and penetration depth increase, the destructive effect of ultrasonic wave is initially increased and then follows by a decreasing trend. With the increasing power of ultrasonic, ultrasonic intensity increases and leads to reducing number of E.coli in sour cherry juice. The increase in time of treatment with ultrasonic causes a decrease in the number of E.coli in sour cherry juice. This is due to the fact that the increase of ultrasonic exposure time leads to the increase of sonic stream in reactor and results in higher contributions of ultrasonic waves to E.coli. Finally, the examined variables were optimized by RSM and the values of ultrasonic power, waves exposing time, probe diameter, and probe penetration depth were obtained as 600 W, 15 min, 35.31 mm, 20.83 mm, respectively. Considering the mentioned values, the amount of E.coli bacteria reduction was estimated to be 1.97 logarithmic period.
Conclusions:
1. Increasing probe diameter and probe depth increasesthe destructive effect of ultrasonic wave.
2. The examined variables were optimized by RSM and the values of ultrasonic power, waves exposure time, probe diameter, and probe penetration depth were obtained as 600W, 15 min, 35.31 mm, 20.83 mm, respectively. Considering the optimum values, the amount of E.coli bacteria reduction was estimated to be 1.97 logarithmic period.
3. With the increasing power of ultrasonic waves, ultrasonic intensity increases and leads to a reduction of the number of E.coli in sour cherry juice.
4. The increase in time of treatment with ultrasonic causesa decrease in the number of E.coli in sour cherry juice.
H. Maghsoudi; S. Minaei; B. Ghobadian; H. Masoudi
Abstract
Electronic canopy characterization to determine structural properties is an important issue in tree crop management. Ultrasonic and optical sensors are the most used sensors for this purpose. The objective of this work was to assess the performance of an ultrasonic sensor under laboratory and field conditions ...
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Electronic canopy characterization to determine structural properties is an important issue in tree crop management. Ultrasonic and optical sensors are the most used sensors for this purpose. The objective of this work was to assess the performance of an ultrasonic sensor under laboratory and field conditions in order to provide reliable estimations of distance measurements to apple tree canopies. To achieve this purpose, a methodology has been designed to analyze sensor performance in relation to foliage distance and to the effects of interference with adjacent sensors when working simultaneously. Results showed that the average error in distance measurement using the ultrasonic sensor in laboratory conditions was 0.64 cm. However, the increase of variability in field conditions reduced the accuracy of this kind of sensors when estimating distances to canopies. The average error in such situations was 3.19 cm. When analyzing interferences of adjacent sensors 30 cm apart, the average error was ±14.65 cm. When adjacent sensors were placed apart by 60 cm, the average error became 6.73 cm. The ultrasonic sensor tested has been proven to be suitable to estimate distances to the canopy in pistachio garden conditions when sensors are 60 cm apart or more and can, therefore, be used in a system to estimate structural canopy parameters in precision horticulture.
B. Jamshidi; S. Minaei; E. Mohajerani; H. Ghassemian
Abstract
In recent years, application of near-infrared spectroscopy (NIR) as a non-destructive technique combined with chemometric methods has been widely noticed for quality assessment of food and agricultural products. In chemometric methods, quality analyses are important issues which could be related to pattern ...
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In recent years, application of near-infrared spectroscopy (NIR) as a non-destructive technique combined with chemometric methods has been widely noticed for quality assessment of food and agricultural products. In chemometric methods, quality analyses are important issues which could be related to pattern recognition. In this research, the feasibility of pattern recognition methods combined with reflectance NIR spectroscopy for non-destructive discrimination of oranges based on their tastes was investigated. To this end, both unsupervised and supervised pattern recognition techniques, hierarchical cluster analysis (HCA) and soft independent modeling of class analogies (SIMCA) were used for assessing the feasibility of variety discrimination and classification (according to their taste), respectively, based on the spectral information of 930-1650nm range. Qualitative analyses indicated that NIR spectra of orange varieties were correctly clustered using unsupervised pattern recognition of HCA. It was also concluded that supervised pattern recognition of SIMCA for NIR spectra of oranges provided excellent results of variety classification based on BrimA index at 5% significance level (classification accuracy of 98.57%). Moreover, wavelengths of 1047.5nm, 1502nm, and 1475nm contributed more than other wavelengths in discriminating two classes. Samples having the same BrimA index were also correctly classified with the high classification accuracy (95.45%) at 5% significance level. The discrimination power of wavelengths of 1475nm, 1583nm, and 1436.75nm were more than those for other wavelengths to achieve this classification. Therefore, reflectance NIR spectroscopy combined with pattern recognition methods can be utilized for determination of other attributes related to taste.
S. M. Ataei Ardestani; B. Beheshti; M. Sadeghi; S. Minaei
Abstract
Fluidized bed dryers have not yet been used for drying products such as mint leaves. This could be due to high porosity and low mechanical resistance resulting in poor quality of fluidization. Applying vibration has been recommended to overcome problems such as channeling and defluidization, and hence ...
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Fluidized bed dryers have not yet been used for drying products such as mint leaves. This could be due to high porosity and low mechanical resistance resulting in poor quality of fluidization. Applying vibration has been recommended to overcome problems such as channeling and defluidization, and hence improving the fluidization quality. In this research, a laboratory scale vibro-fluidized bed heat pump dryer was designed and constructed for drying mint leaves. The experiments were conducted at vibration frequency of 80 Hz and amplitude of 3 mm. The velocity and temperature of the inlet air was controlled by an automatic control system. Experiments were carried out at 40, 50 and 60 °C, and two methods: heat pump drying (HPD) and non-heat pump drying (NHPD). The results revealed that drying process primarily occurred in the falling rate period. Effective moisture diffusivity of the samples increased with increase in drying air temperature and varied from 4.26656×10-11 to 2.95872×10-10 m2 s-1 for the HPD method, and 3.71918×10-11 to 1.29196×10-10 m2 s-1 for the NHPD method and was within the reported range of 10-9 to 10-11 m2 s-1 for drying of food materials. The activation energy was determined to be 84 kJ mol-1 for the HPD and 54.34 kJ mol-1 for the NHPD, both have very good agreement with the results of other investigators. The coefficient of performance and specific moisture evaporation rate showed the acceptable performance of the heat pump system. Moreover, the energy consumption of the dryer for the NHPD method was more than the HPD method.
H. Goli; S. Minaei; A. Jafari; A. R. Keyhani; A. Hajiahmad; H. Abdolmaleki; A. M. Borghaee
Abstract
In this research, four different positioning methods were compared in order to evaluate their accuracy, using a remotely controlled robot on a specific route. These methods included: using a single GPS module, combining the data from three GPS modules, using an Inertial Measurement Unit (IMU), and GPS/IMU ...
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In this research, four different positioning methods were compared in order to evaluate their accuracy, using a remotely controlled robot on a specific route. These methods included: using a single GPS module, combining the data from three GPS modules, using an Inertial Measurement Unit (IMU), and GPS/IMU data fusion. The comparison of these four methods showed that GPS/IMU data fusion along with a Kalman filter was the most precise method, having a root mean square error of 23.4cm. Integrating the data acquired simultaneously from three GPS modules with fixed and equally spaced position and far enough from each other, had a root mean square error of 31.3cm was the second most precise method. . Also analysis of the IMU data showed that due to cumulative errors, it was not a suitable method using a single IMU for positioning.
R. Meamar Dastjerdi; S. Minaei; M. H. Khoshtaghaza
Abstract
Development of ultrasound technique has not been progressing for evaluating the internal quality of fruits as fast as that of processed foods. In this research for quality assessment of pear fruit (Shah Miveh variety) an ultrasonic measurement system was constructed to transmit and receive the ultrasonic ...
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Development of ultrasound technique has not been progressing for evaluating the internal quality of fruits as fast as that of processed foods. In this research for quality assessment of pear fruit (Shah Miveh variety) an ultrasonic measurement system was constructed to transmit and receive the ultrasonic waves. The apparatus included a pulser-receiver, a pair of 75 kHz ultrasonic transducers with exponential horn, and a computer system for data acquisition and analysis. Several mechanical and chemical properties, including firmness, TSS, acidity, elastic modulus, pH and total dry matter for destructive quality assessment were measured. Velocity and attenuation of ultrasonic waves for nondestructive tests were also measured. The fruit quality levels for the experiment were: unripe, ripe and overripe. The results of tests showed that firmness was the best parameter for measuring fruit quality, as it decreased significantly with ripeness. The effect of ripeness on the velocity and attenuation of ultrasonic waves was also significant. Investigation showed a positive linear relationship between fruit firmness and wave velocity (R2=0.81). Furthermore, the relationship between fruit firmness and attenuation was exponential and wave attenuation decreased with increasing fruit firmness (R2=0.895). The Relationship between ultrasonic properties and fruit modulus of elasticity showed that the wave velocity increased and attenuation decreased with increasing elasticity. It can be concluded that the ultrasonic instrument equipped with exponential horns can effectively be utilized for pear quality assessment based on measurement of wave velocity and attenuation.
K. Abbasi; M. Almassi; A. M. Borghaee; S. Minaei
Abstract
Agricultural mechanization is a method for transiting from traditional agriculture towards industrial and sustainable one. Due to the limitation of natural resources and increasing population we need to have economical production of agricultural crops. For reaching this destination; agricultural mechanization ...
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Agricultural mechanization is a method for transiting from traditional agriculture towards industrial and sustainable one. Due to the limitation of natural resources and increasing population we need to have economical production of agricultural crops. For reaching this destination; agricultural mechanization has a remarkable role. So it is necessary to have an extensive view for mechanization, because with the help of mechanization the agricultural inputs such as seeds, fertilizer and even water and soil can effectively be managed for an economical and sustainable production. This study has been carried out in many provinces of Iran. The data of agricultural tractors and cereal combine harvesters were firstly gathered by means of questionnaire. The tractors were categorized in four power levels of less than 45, 45 to 80, 80 to 110, and more than 110 hp. In addition, it was also carried out for cereal combine harvesters; it was in three power levels, i.e. between 100 to 110, 110 to 155 and 155 to 210 horse-power in 3 ages, i.e. less than 13, between 13 to 20, and more than 20 years. Information regarding to cultivation areas, production volume, and yield of main crops gathered from statistics of Ministry of Jihad-e-Agriculture. Then agriculture mechanization level index (hp ha-1) in each province was calculated. Four main crops including irrigated and rain-fed wheat and irrigated and rain-fed barley, which met the required criteria to be used in the model, were statistically analyzed. Correlation analysis was carried out in order to get an effective model between yield of the four main crops in Iran and agriculture mechanization level index. Pearson correlation index showed that there is a direct and significant correlation between these variables. Subsequently, outliers were identified in order to get a model with necessary efficiency to predict the yield through mechanization level index, by scatter diagram and estimating regression lines in 1% probability level. The effective model was estimated with acceptable coefficient of determination 0.851, after removing outliers.
S. Abbasi; S. Minaei; M. H. Khoshtaghaza
Abstract
In this study thin layer drying of corn in a convective dryer was investigated at air temperatures of 50, 60 and 70ºC and air flow rates of 1, 1.4 and 1.8 kg min-1. Experiments were performed in Completely Randomized Design (CRD). The effect of air temperature and flow rate on drying time, drying ...
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In this study thin layer drying of corn in a convective dryer was investigated at air temperatures of 50, 60 and 70ºC and air flow rates of 1, 1.4 and 1.8 kg min-1. Experiments were performed in Completely Randomized Design (CRD). The effect of air temperature and flow rate on drying time, drying rate, effective diffusivity coefficient and activation energy were studied. Results showed that the effects of temperature and flow rate on drying process were significant. Increasing the air temperature from 50 to 70 ˚C, caused 31.7 percent decrease in drying time and change of air flow rate from 1 to 1.8 kg min-1 reduced drying time 27 percent in average. The effective diffusivity coefficient and activation energy varied from 3.47258 ×10-11 to 7.34352×10-11 m2 s-1. and 13.761 to 16.193 kJ mol-1, respectively depending on the drying treatments. The Logarithmic model was found to be in a better agreement with experimental data compared with other models. The minimum value of specific energy requirement (3.61 kWh kg-1) was obtained at a drying air temperature of 50 °C and air flow rate of 1 kg min-1, whereas the corresponding parameters for the maximum value (5.34 kWh kg-1) were determined as 70 °C and air flow rate 1.8 kg min-1.
R. Mirzaei; S. Minaei; M. H. Khoshtaghaza; A. M. Borghaee
Abstract
The most important quality indicator of fruits is the flesh firmness which is well correlated to their young’s modulus. In this research variation of vibration characteristics (shape modes, natural frequency) of apple due to change of material characteristics (density, young's models, Poisson ratio) ...
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The most important quality indicator of fruits is the flesh firmness which is well correlated to their young’s modulus. In this research variation of vibration characteristics (shape modes, natural frequency) of apple due to change of material characteristics (density, young's models, Poisson ratio) and apple volume was investigated using Finite Element simulation. An image processing technique was used to obtain an unsymmetrical and non-spherical geometric model of apple. The exact three-dimensional shape of the fruit was created by determining the coordinates of apple surface and forming uneven rotational curvatures. Modal analysis with no boundary constraints has been applied. The first 20 Eigen frequencies and the corresponding mode shape were determined. Six rigid body modes possess zero resonant frequency which is related to the degree of freedom of a rigid body in space indicated the validity of finite element model. The modal analysis results showed that resonant frequency increased by increasing young's modulus of the fruit, while it decreased by increasing apple density. First mode torsion has a mean resonant frequency of 584 Hz. Variations of natural frequency due to change in young's modulus, density, and Poisson ratio were 80%, 11% and 4%, respectively. Coefficient of variation of resonant frequency in response to changing young's modulus was 2-3 times of that of density which shows the greatest effect of young modulus changes on natural frequency of fruits. Consequently with determination of fruits' natural frequency, their young modulus and firmness can be estimated.
Design and Construction
R. Meamar Dastjerdi; S. Minaei; M. H. Khoshtaghaza
Abstract
Non-destructive ultrasonic testing is one of the methods utilized to evaluate quality of agricultural produce. Transducers used in this method are made for basically industrial applications. Since ultrasonic attenuation of waves in agricultural produce is very high, industrial transducers cannot be used ...
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Non-destructive ultrasonic testing is one of the methods utilized to evaluate quality of agricultural produce. Transducers used in this method are made for basically industrial applications. Since ultrasonic attenuation of waves in agricultural produce is very high, industrial transducers cannot be used in agriculture and needs to be modified. This is done with horns that concentrate energy on a small area at a certain distance from the transducer. In this paper, an exponential horn was designed, fabricated and tested using theoretical and computer-aided methods. Results showed that highly sophisticated horns can be designed using computer-aided method with a high accuracy. Analysis of the number of elements on the natural frequency of horn proved that the analysis was not precise at the low number of elements. Therefore, the number of elements should be increased when natural frequency of horn is almost fixed. The minimum number of elements was obtained to be 300. A comparison between theoretical and computer-aided methods showed a desirable performance of the computer-aided method with an error less than 1% without solving very complicated equations. Based on statistical analysis of the data, the effect of produce thickness (potato and carrot) on the velocity of ultrasonic waves in the horned probe was not significant. However, for the un-horned probe, velocity changed significantly with the sample thickness which is not desirable. Therefore, horned probe is more suitable for non-destructive ultrasonic tests than the un-horned probe.
D. Mohammad Zamani; S. Minaei; R. Alimardani; M. Almassi; R. Yusefi
Abstract
In this study evaluation and comparison of various interpolation approaches for estimation un-sampled values of soil Organic Matter Content (OMC) and soil texture is presented. The main objective is to develop a precision method for generation of management maps for variable rate application of herbicide ...
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In this study evaluation and comparison of various interpolation approaches for estimation un-sampled values of soil Organic Matter Content (OMC) and soil texture is presented. The main objective is to develop a precision method for generation of management maps for variable rate application of herbicide that eventuate to save herbicide application and to reduce adverse impact on the environment. For this purpose after sampling of 42 points on the test field and generation of local and global grid of sample points on a PC, various interpolation methods were applied to estimate soil OMC and texture on un-sampled points by Surfer software. Inverse distance to a power, Kriging, minimum curvature, weighed moving average and radial basis function were used as interpolators. To evaluate the mentioned methods, cross-validation approach and two statistical parameters MAE and MBE were used. The results showed that minimum curvature method with MAE equal to 1.31 has the minimum error than other methods. In this method MAE value for sand, silt and clay was equal to 1.6, 1.18 and 0.59, respectively. In comparison with other methods, this approach had the minimum error. It was demonstrated that minimum curvature method was the best approach to estimate grid point values at un-sampled points. Finally after selection of appropriate method and using considered manufacturer recommendations of herbicide application based on OMC and soil texture, a digital management map of Cyanazine variable rate application in a corn field was generated. Based on this map and considering the herbicide uniform application in the farm as 1.7, 2.9 and 4 Lha-1, herbicide application rate compared with 1.8 Lha-1, decreases 39% and increases 4 and 50% respectively. This means that if the entire field is sprayed with the uniform rate of 1.7 Lha-1, Compared with1.8 Lha-1 which is obtained using management map, herbicide application will be saved 39 %. Similarly, if herbicide is applied 2.9 and 4 Lha-1 uniformly, compared to the amount 1.8 Lha-1, 4 and 50% of herbicide application will increase respectively.
