Modeling
M. Dana; P. Ahmadi Moghaddam
Abstract
IntroductionToday, the development of the livestock industry and feed supply is a vital issue due to the growing world population, the importance of animal protein supply, and the growing requirement for livestock products.A porous medium refers to a solid-void (pore) space that is occupied by a fluid ...
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IntroductionToday, the development of the livestock industry and feed supply is a vital issue due to the growing world population, the importance of animal protein supply, and the growing requirement for livestock products.A porous medium refers to a solid-void (pore) space that is occupied by a fluid (gas or liquid). Generally, many of these pores are interconnected which makes the transportation of mass and heat possible through the pores and this contributes to a faster transportation process through the solid matrix. Porosity is the fraction of void space to total volume.While the pores are large enough, water vapor and air in the porous media can be transported by molecular diffusion. Molecular diffusion of a gas species (e.g., vapor) in a gas mixture (e.g., vapor and air) is described by Fick’s law.Materials and MethodsIn this study, the samples were classified into four categories, including control, 3-impacts (low conditioning), 8-impacts (average conditioning), and 13-impacts (high conditioning). Each category included six samples (50-grams) that were used to measure different characteristics at different stages. All samples were weighed every two hours using a digital scale (0.001 gr precision). The leaf-stem separation force then was extracted using a texture analyzer. All experiments were repeated three times, and finally, the mean of these three repetitions was reported as the final value for the intended parameter.The geometry of the alfalfa stem was drawn in Gambit software and after meshing and applying boundary conditions; it was transferred to ANSYS Fluent software. Then, while the solver was selected, adjusted under relaxation factors were applied. In the following, mesh independency was checked and the results were reported.Results and DiscussionTo ensure numerical accuracy, the experimental data should be validated with the simulation results. For this purpose, experimental moisture losses were compared to the software results and showed a good agreement. Then, the moisture ratio curves (kinetics of drying) and force-time chart were presented.The impact of the moisture content of the tissue was evaluated on the value of force per time. Therefore, three samples of alfalfa with different relative humidity in terms of leaf-stem separation force were reported.The results of the numerical simulations were presented as two main contours: the velocity magnitude and moisture (water vapor) mass fraction. The simulation results were provided for all different modes and compared to the experimental data. Finally, errors between both results were presented in a table.ConclusionRegarding the quality and losses of the final product and comparisons between four different modes (control, 3 impacts, 8 impacts, and 13 impacts), the mode with 8 impacts was selected as the best mode.The Force-time chart illustrated two peaks due to the special multi-layer texture of the alfalfa. Regarding reducing the moisture ratio of the alfalfa as compared to the optimal, the force required to separate the leaves from the alfalfa stem was significantly decreased. Also, a significant increase in the losses was observed for impacts modes higher than 8.
I. Golpour; P. Ahmadi Moghaddam; A. M. Nikbakht
Abstract
IntroductionSteam generation system is a crucial and essential part of food industries which generates and distributes steam for consumption in domestic production units. Energy analysis based on the first law of thermodynamics was employed as the basic approach to assess energy systems. However, the ...
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IntroductionSteam generation system is a crucial and essential part of food industries which generates and distributes steam for consumption in domestic production units. Energy analysis based on the first law of thermodynamics was employed as the basic approach to assess energy systems. However, the energy approach does not provide information on the degradation of the energy quality occurring within energy systems and is, therefore, insufficient for sustainable design or optimization goals. Nevertheless, exergy analysis based on both the first and second laws of thermodynamics can overcome shortcomings of energy analysis. In the present study, the performance of equipment of the steam generation system in Pakdis’s juice production Company located in Urmia is investigated. Owing to the energy and exergy analyses, the sites with the highest loss of exergy are identified as the critical points of the process.Materials and MethodsIn this study, the steam generation unit of a juice production company located in Urmia, West Azarbaijan province in Iran was exergetically analyzed. Using mass, energy, and exergy balances for each component of the unit, the thermodynamic objective functions including the exergy efficiency, exergy destruction rate, exergy loss rate, and the potential improvement rate were assessed. After data acquisition, energy and exergy analysis of this unit was achieved by solving the related equations with the help of thermodynamic properties along with programming in EES software package.Results and DiscussionThe results showed that the highest exergy efficiency of 98.44% was assigned to the steam distributor (O) of the unit with a potential improvement rate of 1.51 kW and an exergy loss rate of 68.80 kW, as well as the pump (M) before the fourth boiler with an exergy efficiency of 19.69%, had the lowest value of exergy efficiency. The values of 12.55 and 11.93 kW were obtained for the exergy destruction rate and its potential improvement rate, respectively. The highest exergy destruction rate of the unit was for the first boiler with a value of 12391.80 kW, with an efficiency of 19.55% and a potential improvement rate of 10295.26 kW.ConclusionWith regard to the energy and exergy analyses of the steam production system, more than 98% of the exergy destruction rate of the entire steam generation system was assigned to boilers, which had a major contribution to the exergetic efficiency of the system. The highest percentage of potential improvement was related to the first boiler and also the third boiler had the highest exergy loss rate, although the lowest exergy loss rate was the expansion tank of the system. In general, this study demonstrated the importance of exergy analysis for detecting the system components with the highest exergy destruction, which can be a breakthrough to identify these components and provides suitable solutions to improve the overall exergy efficiency of the steam-generating system.
S. Babazadeh; P. Ahmadi Moghaddam; A. Sabatyan; F. Sharifian
Abstract
The overall objective of this research is to check the abilities of two non-destructive techniques, the digital imaging (DI) and laser light backscattering imaging (LLBI), on detection of α-solanine toxicant in potatoes. Potato samples were classified in healthy and toxic categories based on the ...
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The overall objective of this research is to check the abilities of two non-destructive techniques, the digital imaging (DI) and laser light backscattering imaging (LLBI), on detection of α-solanine toxicant in potatoes. Potato samples were classified in healthy and toxic categories based on the amount of α-solanine. For quantifying α-solanine in potato tubers, high-performance liquid chromatography (HPLC) has been used. The results of classification showed that single layer perceptron neural networks can classify potatoes with the accuracies of 94.28% and 98.66% by DI and LLBI systems (Donald cultivar), respectively. It can be said that LLBI systems might take precedent over DI systems due to their high accuracy, rapidity, and industrial capability.
F. Jannatdost; P. Ahmadi Moghaddam; F. Sharifian
Abstract
Introduction Fruits and vegetables play an important role in food supply and public health. This group of agricultural products due to high humidity are perishable and most of them (5 to 50 percent) waste during post-harvest operation. Decreasing and minimizing such waste as "hidden harvest" could be ...
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Introduction Fruits and vegetables play an important role in food supply and public health. This group of agricultural products due to high humidity are perishable and most of them (5 to 50 percent) waste during post-harvest operation. Decreasing and minimizing such waste as "hidden harvest" could be an effective way to save food and increase profitability. Despite the surplus of the fruit production in the country, our position in terms of exportation is not commensurate with production, so measurements and grading on the basis of qualitative parameters such as firmness, taste, color, and shape can influence the marketing and export of fruit. In this research, application of an acoustic test is considered to achieve an effective and economic technology in the field to determine the stiffness of kiwifruit in post-harvest step. The aim of this study is to investigate the stiffness index of kiwifruit and provide a classification algorithm in the post-harvest step by using the non-destructive method of processing impact acoustic signals. Materials and Method In this research, an acoustic-based intelligent system was developed and the possibility of using the acoustic response to classify kiwifruit into soft, semi-soft and stiff categories was studied. 150 samples of Hayward variety of Kiwifruit was used during the 18 days shelf life in controlled conditions of temperature and humidity. Analyses were done in 9 sets per two days. In each analysis, an acoustic test was done by 48 samples in both free fall condition and fall from a conveyor belt. The feature extraction of acoustic signals in both the time domain and frequency domain has done, then the classification of samples was done by using the Artificial Neural Network. After getting the impact signals of stiff, semi-soft and soft samples, stiffness of kiwifruits identification has done by using acoustic features. The stiffness of kiwifruit samples in this study was measured to be 15.9±4.9 (N) by using the Magnes- Taylor test. Finally, samples were classified into stiff, semi-soft and soft by comparison of maximum force and flux of signals amplitude. Results and Discussion The results showed that the features of CF and maximum amplitude in the time domain have high accuracy in kiwifruit classification. The frequency resonances as environmental noises or impact position are out of control in the time domain which causes a decrease in accuracy. So, the ANN by features of time domain has not the acceptable capability to identify the semi-soft samples. The identification of semi-soft samples is not easy because of having same properties of stiff and soft samples. Extracted features of frequency domain have the most capability of correct detection. The optimal network has five neurons in the hidden layer and 0.014782 of mean square error. The accuracy of correct detection of the optimal network was 93.3, 91.3 and 78.3 percent for stiff, semi-soft and soft samples, respectively. Because of using more features in the frequency domain, the classification of all categories was acceptable and identification of semi-soft samples was as good as stiff and soft samples. The results of combined features of time and frequency domain showed that the artificial neural network has less efficiency in comparison with the other two attitudes. The accuracy of identification and classification was decreased by adding the extracted features of the time domain. So achieving the most accuracy in classification is accomplishable just by using the features of the frequency domain. By comparing the results of both free fall and online tests, it is claimed that this research can be industrialized. Conclusion Comparison of all results shows that there was no significant difference in the capability of ANN for identification and classification of the sample in three categories. After all, we can use this method in online sorting of kiwifruits by controlling the vector and position of impaction.
Image Processing
P. Ataieyan; P. Ahmadi Moghaddam; E. Sepehr
Abstract
Introduction The color of soil depends on its composition and this feature is easily available and rather stable. Fast and accurate determination of soil organic matter distribution in the agricultural fields is required, especially in precision farming. General laboratory methods for determining the ...
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Introduction The color of soil depends on its composition and this feature is easily available and rather stable. Fast and accurate determination of soil organic matter distribution in the agricultural fields is required, especially in precision farming. General laboratory methods for determining the soil organic carbon are expensive, time-consuming with many repetitions, and high consumption of chemicals. Soil scientists use the Munsell soil color diagrams to define the soil color. Due to the nature of Munsell color diagrams; this system is less suitable for recognizing exact color of the soil because of weak relationship and limited number of chips. Fast methods like image processing, colorimetric and spectroscopy provide a description of most physical characteristics of the soil color. Some of the advantages of using digital cameras was used in this study, are simple sampling of screened soil, being free from chemicals and toxic materials and being fast, inexpensive and precise. Materials and Methods In this research, 80 A-horizon (0-10 cm) soil samples were collected from various agricultural soils in west Azerbaijan, in the North West of Iran. Soil texture of these fields was loam clay and clay. The amount of organic carbon in samples was determined. The camera was installed at the distance of 0.5 m from the Petri dish on the lighting compartment. Captured images with the digital camera were saved in RGB color space. Processing operations were done by MATLAB 2012 software. The features extracted from the color images are used to model the soil organic carbon including the color features in different spaces. Four-color spaces including RGB, HSI, LAB and LUV were studied to find the relation between the color and the soil organic carbon. Results and Discussion The correlation of R component in the RGB model shows a strong single-parameter relation with the organic carbon as R2=0.83. This good relationship can be due to the compound information of the red color component on both brightness and chromaticity dimension. The results also show that the organic carbon has a relatively strong correlation with the light parameters, intensity and lightness in the HSI, Lab and LUV color spaces respectively. It also has a weak correlation with other parameters, since they cannot have a proper linear correlation with organic carbon due to their structural nature. Results show that the highest correlation is obtained when the R and G components participate in modeling and the component B is omitted. One explanation of this high correlation could be the high sensitivity of component B to the intensity and the angle of light. Even a small change in light changes this component. Thus, in order to reduce the effect of this component, it is better to omit it from the models and make models independent of it. In next section, 51 data were used to train neural network, 14 data were used to test the network and 12 data for network validating. The amount of soil organic carbon was output of the neural networks that was estimated after training using the color component values of each segment. To assess the accuracy of the network, estimated values and actual values of each sample were plotted in a graph. The minimum MSE values were 7.28e-6 with 16 neurons, 3.77e-6 with 14 neurons, 4.8e-3 with 10 neurons and 3.77e-6 with 12 neurons for RGB, HSI, Lab and LUV color spaces respectively. Conclusion The availability of digital cameras, possibility to use it in different situations, being inexpensive and providing many samples are the advantages of this method to estimate the soil organic carbon amount. Therefore, digital photography can be used as an analytical method to evaluate the soil fertility. It also requires a low cost of sample testing, and can provide a good possibility of time and place classification for studying a vast area. However to develop more reliable models, more effort is needed, such as collecting more soil samples of different areas that include a wide range of soil features.
P. Ahmadi Moghaddam; L. Eftekhari; A. Mardani; H. Khodaverdilo
Abstract
Introduction: Monitoring and management of soil quality is crucial for sustaining soil function in ecosystem. Tillage is one of the management operations that drastically affect soil physical quality. Conservation tillage methods are one of the efficient solutions in agriculture to reduce the soil erosion, ...
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Introduction: Monitoring and management of soil quality is crucial for sustaining soil function in ecosystem. Tillage is one of the management operations that drastically affect soil physical quality. Conservation tillage methods are one of the efficient solutions in agriculture to reduce the soil erosion, air pollution, energy consumption, and the costs, if there is a proper management on the crop residues. One of the serious problems in agriculture is soil erosion which is rapidly increased in the recent decades as the intensity of tillage increases. This phenomenon occurs more in sloping lands or in the fields which are lacking from crop residues and organic materials. The conservation tillage has an important role in minimizing soil erosion and developing the quality of soil. Hence, it has attracted the attention of more researchers and farmers in the recent years.
Materials and Methods: In this study, the effect of different tillage methods has been investigated on the crop residues, mechanical resistance of soil, and the stability of aggregates. This research was performed on the agricultural fields of Urmia University, located in Nazloo zone in 2012. Wheat and barley were planted in these fields, consecutively. The soil texture of these fields was loamy clay and the factorial experiments were done in a completely randomized block design. In this study, effect of three tillage systems including tillage with moldboard (conventional tillage), tillage with disk plow (reduced tillage), chisel plow (minimum tillage) and control treatment on some soil physical properties was investigated. Depth is second factor that was investigated in three levels including 0-60, 60-140, and 140-200 mm. Moreover, the effect of different percentages of crop residues on the rolling resistance of non-driving wheels was studied in a soil bin.
The contents of crop residues have been measured by using the linear transects and image processing methods. In the linear transects method, the experiments were replicated three times in each block due to increasing the accuracy and mean of datawas calculated. The tests were randomly performed in each block. Then, the number of nodes, which are located on crop residues of size 25 mm, longitudinally, was counted. So the percentage of crop residue in each block was calculated through the percentage of nodes. The experiments of rolling resistance were also performed in three levels, 10, 50, and 90% of crop residues, inside the soil bin.
Results and Discussion: Result showed that, in comparison with control treatment, tillage operation significantly decreased bulk density (p<0.01), penetration resistance (p<0.01), and aggregates stability (p<0.01), in the soil surface (0-10 cm). Also, the results showed that penetration resistance of soil was increased by depth.
The results of variance analysis in crop residue dataset showed that there were significant differences among the treatments in the terms of crop residues (P<0.05). Because of increasing the intensity of tillage and also the different performance of various tillage tools would mix crop residues with the soil and lead to reduce the crop residues. The consequences revealed that the treatments had significant differences in the terms of mechanical resistance of soil at the confidence level of 5%. The mechanical resistance of soil in three levels of depth had the most and the least contents in chisel and disk plows treatments, respectively. Because of disk plows can powder soil more than other treatments and chisel plows can only make narrow in the soil. The results of investigating the effect of crop residues on rolling resistance of wheels showed that there were not any significant differences between the treatments.
Conclusions: It can be concluded that increasing the tillage intensity would reduce the stability of aggregates. Thus, the least stability of aggregates was obtained when using moldboard plows. However, the most stability was achieved using chisel and disk plows. Finally, disk plough is recommended as an appropriate tool in this research due to the high percentage of crop residues, lower mechanical resistance, lower bulk density, and higher stability of aggregates in the soil. Generally, in short-term period, conservation tillage (reduced tillage and minimum tillage) results the improvement of soil physical quality in comparison with tillage operation. Further studies on long-term effects of various tillage systems are suggested in order to select and implement of optimum tillage method in the region.
P. Ahmadi Moghaddam; Y. Ahmadi; F. Salehi
Abstract
Increasing demand for food production in the recent years has raised the usage of granular fertilizers. Consequently, the growing use of fertilizers has reduced the quality and quantity of crop production. In addition pollution problems such as soil and water (surface and subterranean water) contaminations ...
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Increasing demand for food production in the recent years has raised the usage of granular fertilizers. Consequently, the growing use of fertilizers has reduced the quality and quantity of crop production. In addition pollution problems such as soil and water (surface and subterranean water) contaminations has increased. Consistent spreading of fertilizers in the farmlands is of fundamental rules in conventional framings. In present study, the effects of the number and the arrangement (position) of blades of a single disk fertilizer distributer and for two different fertilizers were investigated in order to obtain optimized distribution of fertilizer. The tests were conducted in factorial arrangement and in a completely randomized model. The variables were the number of blades in three levels of 4, 6 and 8, the blade position angles (in two patterns of radial and non-radial) and the type of fertilizer (phosphate and nitrate). Statistical analysis of results indicated that the number of blades on the disk and type of fertilizer are not effective parameters in order to reach a consistent distribution pattern of fertilizer while the position of blades on the disk has significant influence for this purpose. The best pattern of distribution was obtained from the disk with four non-radial blades and nitrate fertilizer.
