Research Article
Design and Construction
S. Dehghani; S. H. Karparvarfard; H. Rahmanian- Koushkaki
Abstract
Introduction: Automatic guidance of tractors in the mechanized farming practice has taken the attention of agricultural engineers in the last two decades. For this to be truly practical on the farm, it should be economical, simple to operate and entirely contained on the vehicle. Different types of steering ...
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Introduction: Automatic guidance of tractors in the mechanized farming practice has taken the attention of agricultural engineers in the last two decades. For this to be truly practical on the farm, it should be economical, simple to operate and entirely contained on the vehicle. Different types of steering systems such as leader- cable, laser- controlled, radio- operated and contactor- type have been developed for automatic guidance. The automatic leveling system is used on hillside machines to keep the separator level when operating on hillsides. This system has three parts: fluid level system, electrical system and hydraulic system. The fluid level system consists of fluid reservoir and a leveling control switch box. The fluid level system actuates the electrical system of the leveling unit. The electrical system which actuated by the fluid system consist of four micro switches in the leveling control switch box, two micro switches in the limit control box, a solenoid in the hydraulic control level, manual leveling control switch, and a leveling limit warning light. The hydraulic system maintains the level of the separator when the machine is operating on a hillside. The present study was aimed to develop a reliable, versatile and easy to maintain system to fit our economy and low technology level of farmers for hillside- range development or fallow farming. The automatic guidance system has been implemented successfully on agricultural vehicles on the basis of three components, i.e. sensors, processors and actuator elements. The study site (N, latitude; E, longitude; and 1810 m above sea level) was located at the Agricultural Research Center, Shiraz University, 15 km northwest of Shiraz, Fars Province, Iran. MF-399 agricultural tractor manufactured by ITMCO, Tabriz, Iran was used for doing the experiments.Materials and Methods:The Level Sensing System: The biaxial tilt industrial sensor (ZCT245AL- China) with digital output can be connected to the computer and received angular position in x and y coordinates. An assumed degree could be considered as basis degree and the measured frequency was adjustable. The tilt sensor located along the axial length of tractor and leads the angles which are created by longitudinal axle transverse axle of the tractor in related to horizontal level. It was used for contour lines detecting. The potentiometer located on the steering wheel of the tractor and pressure sensor which used with goniometer sensor used keeping uniformly of leveling points in tractor motion. The pressure sensor (SN-SCP1000- South Korea) which is used in leveling system can detect the elevation changes. In this way, by defining a limitation of altitude for system, it would be able to stop steering turning motor which was coupled to tractor steering rod automatically. By resetting, the tractor could be able to live in a new level position. To avoid excessive left and right steering wheels deviation and interfering with other lines of travel, potentiometer was used. The deviation degree for steering rod from center to left or right was selected 120 degrees. Accordingly, the wheels would not be able to move more than 10 degrees to each direction. The Processing System: The electrical circuit graphically designed and simulated by software (Altium Designer, 2009) and installed on the tractor. The components of this circuit are as follows: Electrical board, two relays which control the electrical pathway in both directions, a battery with 12 volts of electric potential as electrical power supply, ATmeGA32 microcontroller which was made by Atmel company as main core for information processing, RS232 protocol was used for making correlation between serial port (COM) and the microcontroller and two capacitors for reducing noises. The Actuator System: The output signals from the a processing system, were lead in the actuator system would order and indicative of left- turn or right- turn command, were introduced to actuator- units include an electric- gearbox motor that stimulate the steering wheel shaft of the tractor by chain and sprocket and conduct the tractor in leveling traces at the desired speed. Before hitching any implements such as row planter behind the tractor, the system was successfully tested on average slopes of 14.5% using a tracing powder. Results and Discussion: A plot of the average elevation of each 12 lines traced for a length of about 50 meters, H0, versus the actual elevation of 12 to 16 equally spaced points of each trace, H, produced the following relationship: H0= 0.142+ 0.990 H Indicating a reasonably acceptable performance with standard error and R2 0.048 and 99.3% respectively. Conclusions:The row planting in various slopes coincided with the contour lines of ground (Duncan’s Multiple Range Test p ≤ 0.05). Also, no significant difference was observed among the slopes and index of length and dry weight of root and shoot. The percentage of the emergence index in the high slopes (18-21%) showed significant differences. Hence by increasing slopes, the percentage of seed emergence was decreased.
Research Article
M. Bavafa; M. Tabasizadeh; A. Farzad; B. Ghobadian; H. Eshghi
Abstract
Introduction: Depletion of fossil fuels and environmental degradation are two major problems faced by the world. Today fossil fuels take up to 80% of the primary energy consumed in the world, of which 58% is consumed by the transport sector alone (Mard et al., 2012). The combustion products cause global ...
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Introduction: Depletion of fossil fuels and environmental degradation are two major problems faced by the world. Today fossil fuels take up to 80% of the primary energy consumed in the world, of which 58% is consumed by the transport sector alone (Mard et al., 2012). The combustion products cause global warming, which is caused of emissions like carbon monoxide (CO), sulfur dioxide (SO2) and nitrogen oxides (NOX). Thus it is essential that low emission alternative fuels to be developed for useing in diesel engines. Many researchers have concluded that biodiesel holds promise as an alternative fuel for diesel engines. Biodiesel is oxygenated, biodegradable, non-toxic, and environmentally friendly (Qi et al., 2010). Materials and Methods: In this study transesterification method was used to produce biodiesel, because of its simplicity in biodiesel production process and holding the highest conversion efficiency. Transesterification of poultry fat oil and the properties of the fuels: Fatty acid methyl ester of poultry fat oil was prepared by transesterification of oil with methanol in the presence of KOH as catalyst. The fuel properties of poultry fat oil methyl ester and diesel fuel were determined. These properties are presented in Table 1. Tests of engine performance and emissions: After securing the qualitative characteristics of produced biodiesel, different biodiesel fuels of 5%, 10%, 15%, and 20% blended with diesel fuel were prepared. A schematic diagram of the engine setup is shown in Fig.1. The MF-399 tractor engine was used in the tests. The basic specifications of the engine are shown in Table 3. The engine was loaded with an electromagnetic dynamometer. The Σ5 model dynamometer manufactured by NJ-FROMENT was used to measure the power and the torque of the tractor engine. The speed range and capacity of this device are shown in Table 2. A FTO Flow Meter, manufactured by American FLOWTECH Company, was used to measure the fuel consumption (Fig.3). Its measuring range is 37-1537 ml min-1. Results and Discussion: The engine performance was evaluated in terms of engine power, engine torque and specific fuel consumption at different engine speeds. The variation of engine torques with B5, B10, B15, B20 and diesel fuel are presented in Fig. 4. The engine torque for biodiesel blends was more than that by diesel fuel only. The mean engine torques for B5, B10, B15 and B20 were 2.5%, 2.8%, 3%, and 3.5% higher than that by only diesel, respectively. This is due to the better combustion of biodiesel compared to diesel fuel. The variation of engine powers with B5, B10, B15, B20 and diesel fuel are presented in Fig. 5. The engine powers for biodiesel blends were more than that by diesel fuel. The mean engine powers for B5, B10, B15 and B20 were higher than that by diesel by 2.5%, 3%, 3.5%, and 4%, respectively. This is because of good combustion of biodiesel resulted from higher oxygen content. The mean specific fuel consumptions for B5, B10, B15 and B20 were higher than diesel fuel about 4.1%, 7%, 8.8%, and 2%, respectively (Fig. 8). The density of biodiesel was higher than that of diesel fuel, which means the same fuel consumption on volume basis results in higher specific fuel consumption in case of biodiesel. Conclusions: The values of viscosity, density and flash point of poultry fat oil biodiesel were found to be closely matched with ASTM D-6751 standard specifications. Viscosity and density of biodiesel were found more than those for diesel. The calorific value of biodiesel was found to be lower than that of diesel. Poultry fat oil biodiesel cannot be used as a neat diesel fuel in cold weather conditions due to its relatively low cloud point. Preheating and lowering freezing point is required to eliminate this problem. The engine performance with poultry fat oil biodiesel and its blends are comparable with those of pure diesel fuel. Results indicated that B20 blend had the best performance and the lowest specific fuel consumption.
Research Article
A. Nikkhah; B. Emadi; M. Khojastehpour; S. R. Attarzadeh Hossini
Abstract
Introduction: Too many people are working in the agricultural sector and therefore, pay more attention to the safety and health at work in the agricultural sector is important. This issue is more important in developing industrial countries where the level of the ergonomic working condition is less than ...
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Introduction: Too many people are working in the agricultural sector and therefore, pay more attention to the safety and health at work in the agricultural sector is important. This issue is more important in developing industrial countries where the level of the ergonomic working condition is less than that of developed countries. Attention to ergonomic condition of agricultural machinery drivers is one of the goals of agricultural mechanization. Therefore, in this study the ergonomic conditions of brake and accelerator mechanisms for MF285 and MF399 tractor's drivers were investigated using a new method. Materials and Methods: 25 people were selected for experiment. The electrical activity of Medialis gastrocnemius, Lateralis gastrocnemius, Vastus medialis, Vastus lateralis, Quadratus Lumborum and Trapezius muscles of drivers before and during pressing the pedal and after rest time were recorded using Biovision device. Measurements were performed for each person on each muscle 30 seconds before pressing the pedal, 60 seconds after pressing the pedal and after 60 seconds of rest. For all drivers, the muscles on the right side (brake and accelerator side) have been selected and tested. The measurements were performed in compliance with appropriate time intervals between the measurements. Results and Discussion: Ergonomic assessment of brake pedal: The results showed that the RMS electrical activity of muscles of Vastus medialis and Medial gastrocnemius, during 60 seconds braking were 2.47 and 1.97. So, Vastus medialis and Medial gastrocnemius had the highest stress during pressing the MF399 tractor's brake pedal. Moreover, the Medial gastrocnemius and Lateral gastrocnemius with RMS electrical activity ratio of 2.47 and 1.74 had the highest RMS electrical activity ratio respectively, during 60 seconds braking compared to before braking of MF285 tractor. The comparison of results showed that the Vastus medialis and Trapezius had the higher stress during braking of MF285 tractor than that of MF399 tractor, while, muscles of Medialis gastrocnemius, Lateralis gastrocnemius, Vastus lateralis, Trapezius and Quadratus Lumborum showed the lower stress during braking of MF285 tractor. Ergonomic assessment of accelerator: During 60 seconds pressing the accelerator pedal for MF285 the RMS electrical activity of muscles of Quadratus Lumborum and Medialis gastrocnemius were 3.25 and 2.15. So, these muscles had the highest stress during pressing the accelerator pedal for MF285. Drivers of MF399 tractor experienced high stress in their Vastus lateralis and Lateralis gastrocnemius muscles during pressing the accelerator pedal. The results highlighted that for all muscles, except Vastus lateralis, the electrical activity ratio during pressing the accelerator pedal of MF285 tractor were higher than that for MF399 tractor. Conclusions: To conclude, Vastus medialis and Trapezius had the higher stress during braking of MF285 tractor than that of MF399 tractor, while, muscles of Medialis gastrocnemius, Lateralis gastrocnemius, Vastus lateralis, Trapezius and Quadratus Lumborum showed the lower stress during braking of MF285 tractor as compared with the other model of tractor. Generally in all muscles, except Vastus lateralis, the electrical activity ratio during pressing the accelerator pedal of MF285 tractor was higher than that for MF399 tractor and the drivers need more effort while pressing the accelerator pedal and drivers of this tractor had adverse condition while using the accelerator mechanism. Acknowledgements: The research leading to these results has received funding from the Ferdowsi University of Mashhad, Iran, is gratefully acknowledged. Gratitude also goes to Dr. Mohammad Hossein Abbaspour-Fard, Hossein Fallahi and Mehdi Mahjour for their guidance and support throughout parts of this research.
Research Article
Z. Abdolahzare; M. A. Asoodar; N. Kazemi; M. Rahnama; S. Abdanan Mehdizadeh
Abstract
Introduction: Since the application of pneumatic planters for seeds with different physical properties is growing, it is essential to evaluation the performance of these machines to improve the operating parameters under different pressures and forward speeds. To evaluate the performance of precision ...
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Introduction: Since the application of pneumatic planters for seeds with different physical properties is growing, it is essential to evaluation the performance of these machines to improve the operating parameters under different pressures and forward speeds. To evaluate the performance of precision vacuum seeders numerous procedures of laboratory and field have been developed and their feed mechanism evaluation is of great importance. The use of instrumentation is essential in laboratory procedures. Many systems have been designed, using instrumentation, to be able to monitor seed falling trajectory and as a result, in those systems the precise place of falling seed in the seed bed could be determined. In this study, the uniformity of seed spacing of a seed drill was determined using of high speed camera with a frame rate of 480 frames s-1. So that, the uniformity of planting was statistically significant under the influence of the speed of seed metering rollers (Karayel et al., 2006). Singh et al. (2005) studied the effects of disk rotation speed, vacuum pressure and shape of seed entrance hole on planting spacing uniformity using uniformity indices under laboratory and field conditions. They reported miss index values were reduced as the pressure was increased but they were increased with increasing of the speed. The multiple indices on the other hand were low at higher speed but they were increased as the pressure was increased. Ground speed was affected by changes in engine speed and gear selection, both of which effect on amount of fan rotation speed for different pressures. The aim of this study was to identify and determine the effects of forward speed and optimum vacuum pressure amount of the pneumatic seeder.Materials and Methods: The pneumatic planter (Unissem) was mounted on a tractor (MF399) and passed over the soil bin. Thus, the acquired data would be more reliable and practical. To do so, the tractor was equipped with electronic devices for online measurement of various parameters, including: the actual forward speed, wheel sleep percent, drawbar pull, motor RPM, and fuel consumption. Wheel drive of the seed metering mechanism was equipped with Rotary Encoder model S48-8-0360ZT (TK1) to determine the seed disk rotation. For more precise vacuum pressure monitoring, a Vacuum Transmitter model BT 10-210 was used to measure relative pressure from 0 mbar to -1000 mbar. Investigation of seed falling trajectories was conducted using the AVI video acquisition system consisted of CCD (charge-coupled device) camera (Fuji F660EXR) capable of capturing images with a constant speed of 320 frames per second and a spatial resolution of 320×240 pixels. All data were transmitted to a data logger and displayed online on the PC's screen.For optimization of the factors affecting the performance of the pneumatic planter, the experiments were conducted with: two ranges of forward speeds [3 to 4 km h-1, and 6 to 8 km h-1; three levels of vacuum pressure [-2.5kPa, -3.5kPa and -4.5 kPa]; and two types of seed [cucumber and watermelon], keeping a three-factor factorial experimental design. The tests were replicated three times. The uniformity of seed spacing was measured with indicators described by kachman and smith (1995) which are defined as:I_miss=N_1/N×100 (1)I_mul=N_2/N×100 (2)I_qf=100-(I_mul+I_miss) (3)P=s_d/x_ref (4)Which for planting distance of 45 cm, N1 is number of spacing > 1.5Xref; N2 is number of spacing ≤ 0.5Xref and N is total number of measured spacings, Sd is standard deviation of the spacing more than half but not more than 1.5 times, the set spacings Xref, Imiss is the miss index, Imul is the multiple index, quality of feed index Iq is the percentage of spacings that are more than half but not more than 1.5 times, the set planting distance and P is error index.Results and Discussion: According to the studies on both watermelon and cucumber, the ‘quality of feed index’ value in forward speed rang of 6 to 8 km h-1 was less than one in forward speed rang of 3 to 4 km h-1. Also, the ‘error index’ value in forward speed rang 3 to 4 km h-1 was little rather than forward speed rang of 6 to 8 km h-1, but it was desirable.For watermelon and cucumber seeds, the ‘quality of feed index’ were the maximum with mean of 97% and 87% under vacuum pressures of -2.5 kPa and -4.5 km h-1, respectively and forward speed of 3 to 4 km h-1; so that for cucumber seed in the mention treatment, the ‘miss index’ was lowest with mean of zero.The ‘multiple index’ was highest with mean of 6% at 3 to 4 km h-1 forward speed and vacuum pressures of -4.5 for watermelon seed. Values of this index at both forward speed and three levels of vacuum pressures, for cucumber seed was more than watermelon seed.Miss index values were reduced as the pressure was increased but increased with increasing of speed. With lower vacuum pressure and at higher speeds, the metering disc did not get enough time to pick up seeds, resulting the higher miss indices. On the other hand, the multiple indices were low at higher speed but were increased as the pressure was increased (Panning et al. 2000; Zulin et al. 1991).Conclusions: It was observed that seed spacing uniformity was affected by both speed and pressure but not equally. Extracted regression models showed that the best uniformity of spacing for watermelon seed obtained at the rang of speed of 3 to 4 km/h and pressure of -3.5 kPa with a error in spacing of 7% in laboratory condition. Furthermore, in field condition the best uniformity of the seed space occurred at the pressure of -2.5 kPa and rang of speed of 6 to 8 km/h with a 9% error. Similarly, for cucumber seed results showed that the best uniformity obtained at the rang of speed of 3 to 4 km.h-1 and pressure of -4.5 kPa in laboratory condition, and at the low speed and pressure of -2.5 kPa in the field.
Research Article
H. Izadi; S. Kamgar; M. H. Raoufat
Abstract
Introduction: The quality of agricultural products is associated with their color, size and health, grading of fruits is regarded as an important step in post-harvest processing. In most cases, manual sorting inspections depends on available manpower, time consuming and their accuracy could not be guaranteed. ...
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Introduction: The quality of agricultural products is associated with their color, size and health, grading of fruits is regarded as an important step in post-harvest processing. In most cases, manual sorting inspections depends on available manpower, time consuming and their accuracy could not be guaranteed. Machine Vision is known to be a useful tool for external features measurement (e.g. size, shape, color and defects) and in recent century, Machine Vision technology has been used for shape sorting.
The main purpose of this study was to develop new method for tomato grading and sorting using Neuro-fuzzy system (ANFIS) and to compare the accuracies of the ANFIS predicted results with those suggested by a human expert.
Materials and Methods: In this study, a total of 300 image of tomatoes (Rev ground) was randomly harvested, classified in 3 ripeness stage, 3 sizes and 2 health.
The grading and sorting mechanism consisted of a lighting chamber (cloudy sky), lighting source and a digital camera connected to a computer.
The images were recorded in a special chamber with an indirect radiation (cloudy sky) with four florescent lampson each sides and camera lens was entire to lighting chamber by a hole which was only entranced to outer and covered by a camera lens.
Three types of features were extracted from final images; Shap, color and texture. To receive these features, we need to have images both in color and binary format in procedure shown in Figure 1.
For the first group; characteristics of the images were analysis that could offer information an surface area (S.A.), maximum diameter (Dmax), minimum diameter (Dmin) and average diameters. Considering to the importance of the color in acceptance of food quality by consumers, the following classification was conducted to estimate the apparent color of the tomato;
1. Classified as red (red > 90%)
2. Classified as red light (red or bold pink 60-90%)
3. Classified as pink (red 30-60%)
4. Classified as Turning (red 10-30%, It showed the color green change to pink)
5. Classified as Breakers (red < 10%, It showed the color green change to yellow)
6. Classified as green (The whole fruit area was green)
To estimate the quality of tomato, we need to estimate background of the images. For this purpose we should follow the preocedure as shown in Fig.2.
According to flowcharts shown in Fig.1, our samples will be in the following stages: (Fig.3.)
Fig.4 shows that during the ripening of tomato red color is increased and green color is decreased. Indicating chlorophyll degradation while lycopen started to be produced.
According to figure 6 we utilize the R and G value of tomato for ripening decision. As ripening data we utilize the mean of red and green values of pixels that are used for this goal. For correct processing of last group, edge of images were removed that had incompletely understood of the fruit color and determine color coefficients, the system with slight error could detect all parts of the damage. Quantity of damage area reported in the proportion of the total area of tomato.
In the present work, 5 factors were considered and the linguistic variables corresponding to the values were created in 4 levels: size, color or ripening, a healthy and final level that classified tomatoes in 8 classes. In size level input values were minimum diameter and surface area. These values classified the tomatoes into 3 groups. In color level input values were Red and Green component values. These values were used to classify the tomatoes in 3 group, too. In healthy and unhealthy level, input value was proportion of damage area to tomato total area. This value were used to classify the tomatoes in 2 group. In final level, outputs of previous levels are our inputs now. This values going to classify the tomatoes into 8 final groups.
Results and Discussion: This system can classify the tomatoes in 8 groups just with rules. For this reason we measured the accuracy of the system before training. This values were 70.7, 82.0, 95.7 and 75.5% for size, color, health and final system respectively. For achieving all ability of ANFIS in classifing we done the above measuring after training of machine. The results were 80.9, 89.5, 95.7 and 81% for size, color, health and final system respectively, that indicate the accuracy of the system is raised by 10%. A validation step is done in this study. The accuracy of the system is measured versus a human expert. The classification was done with 60 samples. The accuracies of machine were 75.9, 83.8, 94.2 and 76.5%. Analysis of results with qui-square test indicated that there is no significant difference between machine results and human expert choices.The validation process proved that system is useful in this purpose.
Conclusions: This research was about evaluating of using machine vision and ANFIS in grading machines and done in off-line mode. The research was redirected to the following general conclusions:
1. To obtain an estimate of tomatoes, sample sizes were measured by using calipers and machine vision, the results showed that this system can be used to obtain dimensions.
2. For the purpose of size grading, the small diameter and the surface area of the image was used whichyielded 67% and 62% accuracy for determining the mass, in comparison the ANFIS system performance was precisely 81%.
3. For the purpose of color grading, red and green were used which is a better description of quality. For this the ANFIS system was used for color grading and it performed at 89.5%.
4. For the purpose of sample selection grading (dividing the rotten from the good), optical robot was used. The outcome of system ANFIS and the optical robots had the same results of selection at 95%.
5. In an aggregate or globally, the criteria from the above was used as an input for the grading and classification. Based on these inputs, the ultimate output was consequently categorized into 8 groups. The precision of the division or the selection was determined to be 81.5%.
6. With respect to the testing based on chi-square, it can be determined that this system can replace human workers. In addition, based on the performance and necessary adjustments to the system and its grading criteria better system can be built to replace human workers.
Research Article
Image Processing
A. R. Abdollahnejad Barough; M. Adelinia; M. Mohamadi
Abstract
Introduction: Pistachio nut is one of the most important agricultural products of Iran and it is priced due to the quality and type. One of the significant factors of pistachio cost is its type in terms of shell. Filled split pistachio nut has the most quality and is utilized as nuts, while the closed ...
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Introduction: Pistachio nut is one of the most important agricultural products of Iran and it is priced due to the quality and type. One of the significant factors of pistachio cost is its type in terms of shell. Filled split pistachio nut has the most quality and is utilized as nuts, while the closed shell type has lower cost, at the same time is economically efficient in food industry such as confectionery. Now, pistachio sorting is performed usually by human and sometimes using electromechanical apparatuses. Classification of pistachio by human is time consuming and is done with an unacceptable accuracy, on the other hand, electromechanical and electro optical apparatuses damages pistachio because the mechanism used in them while separating. So, the need to develop automated systems that could be implemented by intelligent ways is evident to increase the speed and accuracy of classification.Materials and Methods: In this study, 300 samples of pistachios contains 100 Filled split, 100 Filled non-split and 100 split blank nuts ones are used. The training set consisted of 60 samples of each type of opened nuts, closed and empty opened shell nuts a total of 180 samples and the evaluation set consisted of 40 samples of each type of opened shell, closed shell and empty opened shell nuts a total of 120 samples. The principle of this study is implemented in two steps: 1) sample imaging and image processing to extract features 2) fuzzy network design based on the characteristics of data and training.To select useful features from the hypothesis, C4.5 decision tree is used. C4.5 algorithm makes a greedy top to bottom search on the hypothesis, and is made by the question what feature must be at the root of the tree. By the help of statistical methods, extracted features from the images were prioritized and the most appropriate features for classification of training set were selected. The algorithm chooses the best features as their number is minimum. Finally, a total amount of the second moment (m2) and matrix vectors of image were selected as features. Features and rules produced from decision tree fed into an Adaptable Neuro-fuzzy Inference System (ANFIS). ANFIS provides a neural network based on Fuzzy Inference System (FIS) can produce appropriate output corresponding input patterns.Results and Discussion: The proposed model was trained and tested inside ANFIS Editor of the MATLAB software. 300 images, including closed shell, pithy and empty pistachio were selected for training and testing. This network uses 200 data related to these two features and were trained over 200 courses, the accuracy of the result was 95.8%. 100 image have been used to test network over 40 courses with accuracy 97%. The time for the training and testing steps are 0.73 and 0.31 seconds, respectively, and the time to choose the features and rules was 2.1 seconds.Conclusions: In this study, a model was introduced to sort non- split nuts, blank nuts and filled nuts pistachios. Evaluation of training and testing, shows that the model has the ability to classify different types of nuts with high precision. In the previously proposed methods, merely non-split and split pistachio nuts were sorted and being filled or blank nuts is unrecognizable. Nevertheless, accuracy of the mentioned method is 95.56 percent. As well as, other method sorted non-split and split pistachio nuts with an accuracy of 98% and 85% respectively for training and testing steps. The model proposed in this study is better than the other methods and it is encouraging for the improvement and development of the model.
Research Article
Image Processing
H. Payman; A. Bakhshipour Ziaratgahi; A. A. Jafari
Abstract
Introduction: Rice is a very important staple food crop provides more than half of the world caloric supply. Rice diseases lead to significant annual crop losses, have negative impacts on quality of the final product and destroy plant variety. Rice Blast is one of the most widespread and most destructive ...
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Introduction: Rice is a very important staple food crop provides more than half of the world caloric supply. Rice diseases lead to significant annual crop losses, have negative impacts on quality of the final product and destroy plant variety. Rice Blast is one of the most widespread and most destructive fungal diseases in tropical and subtropical humid areas, which causes significant decrease in the amount of paddy yield and quality of milled rice.Brown spot disease is another important fungal disease in rice which infects the plant during the rice growing season from the nursery period up to farm growth stage and productivity phase. The later the disease is diagnosed the higher the amount of chemicals is needed for treatment. Due to high costs and harmful environmental impacts of chemical toxins, the accurate early detection and treatment of plant disease is seemed to be necessary.In general, observation with the naked eye is used for disease detection. However, the results are indeed depend on the intelligence of the person performing the operation. So usually the accurate determination of the severity and progression of the disease can’t be achieved. On the other side, the use of experts for continuous monitoring of large farms might be prohibitively expensive and time consuming. Thus, investigating the new approaches for rapid, automated, inexpensive and accurate plant disease diagnosis is very important.Machine vision and image processing is a new technique which can capture images from a scene of interest, analyze the images and accurately extract the desired information. Studies show that image processing techniques have been successfully used for plant disease detection.The aim of this study was to investigate the ability of image processing techniques for diagnosing the rice blast and rice brown spot.Materials and Methods: The samples of rice leaf infected by brown spot and rice blast diseases were collected from rice fields and the required images were obtained from each sample.The images of infected leaves were then introduced to image processing toolbox of MATLAB software. The RGB images were converted to gray-scale. Using a suitable threshold, the leaf surface was segmented from image background and the first binary image was achieved. Leaf image with zero background pixels was obtained after multiplying the black-and-white image to original color image. The resulting image was transformed to HSV color space and the Hue color component was extracted. The final binary image was created by applying an appropriate threshold on the image that obtained from Hue color component.As there was a high color similarity between the symptoms of two diseases, it was not possible to use Hue color component to distinguish between them. Therefore the shape processing was applied.Four dimensionless morphological features such as Roundness, Aspect Ratio, Compactness and Area Ratio were extracted from stain areas and based on these features, disease type diagnosis was performed.Results and Discussion: Results showed that the proposed algorithm successfully diagnosed the diseases stains on the rice leaves. A detection accuracy of 97.4±1.4 % was achieved.Regarding the results of t-test, among the extracted shape characteristics, only in the case of Area Ratio, there was no significant difference between two disease symptoms. While in the case of Roundness, Aspect Ratio and Compactness, a highly significant difference (P<0.01) was discovered and revealed between rice blast and rice brown spot stains. The developed algorithm was capable of distinguishing between disease symptoms with an exactness of over 96.6%. This means that of the 60 samples (30 samples rice blast and 30 samples of rice brown spot); only two were placed in the wrong category.Conclusions: It was concluded from this study that image processing technique can not only accurately determine whether the rice is healthy or infected but also can determine the type of plant disease with reliable precision. Considering the fact that plant diseases spread area by area through the field, early and accurate diagnosis of plant diseases in a part of a farm - which is provided by image processing techniques and machine vision systems – is very useful for timely and effective disease treatment which in turn leads to lower crop losses. Also, by using the site-specific chemical application technologies, the need for chemicals can be minimized, an important factor that can considerably reduce the costs.
Research Article
E. Askari Asli–Ardeh; M. Azad Takchi; A. Hakimi
Abstract
Introduction: In many rural areas, manual threshers are still in use because of the small farming units. However, research sections, have been used manual threshers particularly in breeding unites in many cases due to the low volume of crop. Manual threshers for the first time were manufactured by Iran ...
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Introduction: In many rural areas, manual threshers are still in use because of the small farming units. However, research sections, have been used manual threshers particularly in breeding unites in many cases due to the low volume of crop. Manual threshers for the first time were manufactured by Iran Ashtad Cooperative in two models (T25 and T30) and then they were made available to the farmers across the country. The threshers due to having wire loop drum had a good performance for threshing rice crop. According to the mentioned application, manual threshers expected to have been capable of threshing wheat crop. A type of this thresher (modelT30) was available in University of Mohaghegh Ardabili. Therefore, It was decided that the performance of this thresher was assessed at threshing some common wheat varieties in Ardabil province. Effects of drum speed levels (800, 900 and 1000 rpm) of threshing unit of john deere combine (model 955) on damaged grains percent showed that the minimum of this dependent factor was obtained at two levels of drum speed 800 and 900 rpm, clearance between drum and concave 25 mm and forward speed 1.8 km.h-1 (Lashgari et al., 2008). Research performed by Vejasit and Salokhe (2004) on a axial flow thresher revealed that the threshing efficiency can be 98 to 100% at tests for soybean, drum speed 600 to 700 rpm, feed rate 540 to 720 kg h-1 and grain moisture content 14.34 to 22.77 w.b.%. Alizadeh and Khodabakhshipour (2010) found at moisture content 17 to 23 w.b.% and drum speed 450 to 850 rpm at test of an axial flow thresher on paddy, ,the most damaged grains percent obtained at the most level of drum speed 850 rpm and the least level grain moisture content 17 W.b.%. Threshing losses due to mechanical damaged wheat grains during threshing process were reported 5.0, 8.1, 10.0 and 19.9% at tests at drum speed 800, 900, 1000 and 1100 rpm, respectively, by King and Riddols (1962). The results of research reported by Mitchell and Roundthwaite (1964) on investigation of two varieties of wheat resistance at grain moisture content 15 to 25 w.b.% and drum speed levels 17 to 36 m s-1 showed that damaged grains percent mean were 94.8 and 86.8 % at tests at the least and most drum speed levels.
Materials and Methods: The tests were accomplished with three varieties wheat (Azar2, Sardari and Rasad), three speed drum levels (400, 500, 600rpm) and three feed rate levels (600, 900, 1800 kg h-1). Grain moisture content varied from 12 to 13 w.b. %. For supplying requirement powerof thresher, AMitsubishi diesel motor (13.5 hp) was used. Preliminary tests on these wheat varieties showed that this thresher did not have desired threshing efficiency. Therefore, it was decided to use of a concave with less curvature radius. So that the minimum distance between the drum and concave was 6 mm. For adjustment of drum speed, a digital tachometer (Lutron DT-2236) was used some pulleys were used for transmission power from engine to drum shaft, The weight of each sample was 1 kg. To create different levels of feed rate, crop feeding times were considered 2, 4 and 6 seconds. The factorial experiment in a randomized complete block design has been used for analyzing data, Data mean comparison was done by Duncan's Multiple Test.
Results and Discussions: The results of analysis variance showed that effects of variety of the drum speed and feed rate were significant on threshing losses. Damaged grain percent was negligible. The results of mean comparison showed that the most (15.632%) and the least (4.154%) threshing losses obtained at tests on Azar2 and Rasad varieties, respectively. As increasing feed rate from 600 to 1800 kg h-1, threshing losses was decreased significantly. It was due to clusters compression at between drum and concave. The results of mean comparison of triplet interactions showed that the lowest threshing losses (0.147%) obtained at tests on Rasad variety, feed rate of 600 kg h-1 and rotational speed drum level of 600 rpm. the highest threshing losses (39.387%) obtained at tests on Azar2 variety, feed rate 1800 kg h-1 and rotational speed drum level of 400 rpm.
Conclusions:
1. Modified thresher was not able to thresh Azar2 variety. But it was able to thresh Sardary and Rasad wheat varieties with desirable threshing efficiency.
2. According to low and high threshing losses at tests on Rasad and Azar2 varieties, respectively, It must be conclude that shattering of Rasad variety is very high.
3. Damaged grain percent was negligible at test on each three varieties.
Research Article
M. Feyzi; A. Jafari; H. Ahmadi
Abstract
Introduction: Nowadays most of the agricultural and industrial tasks are performed using different machines and almost any people are exposed to the vibration of these machines. Just as sound can be either music to the ear or irritating noise, human vibrations can either be pleasant or unpleasant. Whole-body ...
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Introduction: Nowadays most of the agricultural and industrial tasks are performed using different machines and almost any people are exposed to the vibration of these machines. Just as sound can be either music to the ear or irritating noise, human vibrations can either be pleasant or unpleasant. Whole-body vibration and hand-arm vibration are two main types of unpleasant vibration. The hand-arm transmitted vibration can cause complex vascular, neurological and musculoskeletal disorder, collectively named as hand-arm vibration syndrome. The chainsaw is a portable machine, powered by a two-stroke engine. This machine is used by tree surgeons to fell trees, remove branches, and other activities such as prune trees. The chainsaw exposes own operators to high level of hand-arm vibration which can lead to problems such as vibration white finger syndrome and Raynaud's phenomenon. White finger syndrome affects the nerves, blood vessels, muscles, and joints of the hand, wrist and arm. It is clear that before trying to control the vibrations, the level of vibrations should be identified. Therefore, an investigation on the vibration level of this machine is crucial.
Materials and Methods: The Stihl-MS230 chainsaw was selected in this study. The size of this type of chainsaw is middle and it is equipped with anti-vibration system. According to the ISO-7505 standard, vibration must be measured at three speed level of engine. First at idling speed, second at nominal speed and third at 133% of the nominal speed or maximum speed of engine whichever is less (Racing). So 2800, 10000, and 13300 RPM Engine speed were selected. One of the employed accessories was ARMA ETI-TACHO tachometer which had been fabricated in Taiwan. The vibrations were measured and analyzed using the portable data acquisition system (Easy Viber). During the measurements, data acquisition system was powered by internal batteries. The vibrations were sensed by the piezoelectric accelerometer (VMI-192). The accelerometer mounted on an adapter inserted between the handle and accelerometer. The experiments were conducted in split plot completely randomized design. Ninety tests in two handles, three speeds of engine, three perpendicular axes and five repeats were conducted. The vibration acceleration at various conditions was measured and the root mean square of vibration acceleration was calculated based on acceleration-time spectrum. To investigate the characteristics of vibration in different speeds, the vibration spectrums in time domain were converted to spectrums in frequency domain. The frequency weighted RMS acceleration at 1/3rd octave bands from 6.3Hz to 1250Hz and the vibration total value was calculated from frequency spectrum. To analyze the obtained data, SAS software was used. Furthermore, the Duncan's multiple range tests were used to compare the RMS values.
Results and Discussion: Main source of vibration of chainsaw was single cylinder engine. The acceleration spectra of employed chainsaw had peaks in frequencies in accordance with the speed of engine. These peaks in 2800 rpm, 10000 rpm and 13300 rpm speeds of engine occurred in 46.5Hz, 166.5Hz and 221.5Hz, respectively. To achieve a safe design for handle of portable tools, identifying the frequency which leads to the maximum value of vibration acceleration is very useful. To avoid the resonance phenomenon, the natural frequency of handle must be far from dominant frequency of engine. The results of ANOVA showed that the RMS acceleration in different axes and different speeds were significant at 1% level. The maximum value of vibration acceleration, at idling engine speed, occurred in the lateral axis. In addition, the mentioned variable was maximized in normal and axial axes at nominal and racing speeds, respectively. The total value of vibration was increased when the speed of engine moving away from nominal speed. This increase in rear handle is very larger than front handle. The total value of vibration was maximized under rear handle and idling engine speed conditions. So the exposure to white finger disorder in right hand of operator is more probable. Total daily duration of exposure was assumed to be equal to 2h. According to the international standard (ISO 5349), 10% of the users can expect developing the symptoms of white finger syndrome less than seven years.
Conclusions: In chainsaw, strokes caused by combustion are the main source of vibration. On the front handle, the maximum value of vibration acceleration, at 2800, 10000 and 13300 RPM engine speed, occurred in the lateral, normal and axial axes respectively. The vibration acceleration value was maximized under rear handle and racing engine speed conditions caused by large value of vibration acceleration at 400Hz center of 1/3rd octave bands. The total value of vibration in idling and racing engine speeds, on rear handle are more than front handle significantly but in nominal engine speed, on rear handle is less than front handle.
Research Article
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.
Research Article
A. Jafari Malekabadi; M. Khojastehpour; B. Emadi; M. R. Golzarian
Abstract
Introduction: Poisson ratio and modulus of elasticity are two fundamental properties of elastic and viscoelastic solids that use in solving all contact problems, including the calculation of stress, the contact surfaces and elastic deformation (Mohsenin, 1986; Gentle and Halsall, 1982).
There are many ...
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Introduction: Poisson ratio and modulus of elasticity are two fundamental properties of elastic and viscoelastic solids that use in solving all contact problems, including the calculation of stress, the contact surfaces and elastic deformation (Mohsenin, 1986; Gentle and Halsall, 1982).
There are many published literature on Poisson ratio and elasticity modulus of fruit and vegetables. Shitanda et al. (2002) calculated Poisson ratio of rice by considering Boussinesq’s theory. They showed that the Poisson ratio is greater for shorter varieties. In another study, researchers used the instrumented bending beam to measure the lateral expansion of red beans. They were considered Poisson ratio as the ratio of transverse strain to the longitudinal strain (regardless of the geometry of the sample) and were calculated modulus of elasticity with Hertz theory for convex bodies (Kiani Deh Kiani et al., 2009). Cakir et al. (2002) was determined the Poisson ratio and elastic modulus of some onion varieties. They used a simple formula to determine the transverse strain that developed by Sitkei (1986) for prism-shaped rod, regardless of the geometry of the product.
Reviewed scientific literature shows that these parameters have not been studied according to the geometric shape of onions and was not used by a more accurate method, such as image processing to determine these parameters. The objective of this study was to evaluate the mechanical properties of two varieties of onions. Poisson ratio was determined with image processing. Considering shape of the onions and deformation value, and using Hertz’s theory with Poisson ratio, modulus of elasticity was calculated. The effects of loading directions (polar or equatorial), deformation value (5, 10 and 15 mm), loading speed (15 or 25 mm min-1) and onion varieties (Red and Yellow) on the modulus of elasticity and apparent Poisson’s ratio were examined.
Materials and Methods: The onions harvested in autumn, 20 days before conducting the tests. Onion samples kept at room temperature (21oC). Onions of each cultivar were randomly selected. Diameters of onion were measured with a digital vernier caliper. In each run, eight onions were randomly selected and the loading test and photography were done together and the average values reported.
All mechanical tests were performed using a Universal Testing Machine (UTM) (Model H5KS, Tinius Olsen Company) between two rigid plates. The loading was made with two constant speeds of 15 and 25 mm min-1. Deformation values were 5, 10 and 15 mm. The onions were loaded either axially or laterally until rupture point and photography were done together.
The initial and current onion diameters along the y and x axes obtained by using image processing and the strains were calculated. Having axially and laterally strains of the onions, the apparent Poisson's ratio was calculated using equation presented by Figura and Teixeira 2007; Kiani Deh Kiani et al., 2009; Pallottino et al., 2011; Kabas and Ozmerzi 2008; Gladyszewska and Ciupak 2009.
A factorial experiment based on a completely randomized design with 8 replications was applied. The significant differences of means were compared by using the Duncan’s multiple range test at 5% significant level. SPSS 20.0 software was used for data analysis.
Results and Discussion: According to the analysis of variance (Table 2), the effects of speed and displacement of loading was significant in 5% probability levels. In addition, interaction effect varieties × directions × speed along Y, varieties × directions, varieties × speed and directions × speed along X was significant in 1, 1, 5 and 5% probability levels, respectively. The average of the apparent Poisson ratio for Yellow onion was less than that obtained for the Red onion, because Red onions have softer texture than Yellow onions. Apparent Poisson ratio was obtained as 0.2623 to 0.4485 and 0.2423 to 0.4179 for Yellow and Red onions, respectively. With increasing deformation, apparent Poisson ratio increased.
Modulus of elasticity along X and Y
According to the analysis of variance (Table 2), the effects of speed and displacement of loading and directions × speed was significant in 1% probability levels. The average of the modulus of elasticity for Red onion was less than that obtained for the Yellow onion because Yellow onion has tougher and more powerful texture than Red onion. Modulus of elasticity were obtained as 2.032 to 5.449 and 1.829 to 5.311 MPa for Yellow and Red onions, respectively. The modulus of elasticity for lateral loading was less than that obtained for the axial loading. With increasing deformation, the modulus of elasticity decreased. The modulus of elasticity for lateral loading in loading speed 25 mm min-1 was less than that obtained for loading speed 15 mm min-1.
Conclusions: The results were summarized as below:
Loading speed, deformation value and their interaction effect were significant in different confidence levels for apparent Poisson's ratio and modulus of elasticity.
The compression force of Yellow onion was more than Red onion. Thus, it can be concluded that Yellow onions have more strength against the forces and loading.
The modulus of elasticity for lateral loading was less than that obtained for the axial loading. It is better to be considered for packaging of onions.
The modulus of elasticity for lateral loading in loading speed 25 mm min-1 was less than that obtained for loading speed 15 mm min-1.
With increasing deformation, the modulus of elasticity and apparent Poisson’s ratio decreased and increased, respectively.
Research Article
M. H. Aghkhani; J. Baradaran Motie
Abstract
Introduction: Separation and grading of agricultural products from the production to supply, has notable importance. The separation can be done based on physical, electrical, magnetic, optical properties and etc. It is necessary for any development of new systems to study enough on the properties and ...
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Introduction: Separation and grading of agricultural products from the production to supply, has notable importance. The separation can be done based on physical, electrical, magnetic, optical properties and etc. It is necessary for any development of new systems to study enough on the properties and behavior of agricultural products.
Some characteristics for separation are size (length, width and thickness), hardness, shape, density, surface roughness, color, speed limit, aerodynamic properties, electrical conductivity, elasticity and coefficient of static friction point.
So far, the friction properties of agricultural products used in the separating process, but the effect of electrostatic charging on static and dynamic coefficients of friction for separation had little attention. The aim of this study was to find out the interactions between electrostatic and friction properties to find a way to separate products that separation is not possible with conventional methods or not sufficiently accurate. In this paper, the separation of close and smiley pistachios by electrostatic charging was investigated.
Materials and Methods: Kallehghoochi pistachio cultivar has the top rank in production in Iran. Therefore, it was used as a sample.
The experimental design that used in this study, had moisture content at three levels (24.2, 14.5 and 8.1 percent), electric field intensity at three levels (zero, 4000 and 7000 V), speed of movement on the surface at three levels (1300, 2500 and 3300 mm per minute), friction surface (galvanized sheet iron, aluminum and flat rubber) and pistachio type at two levels (filled splits and closed) that was measured and analyzed in completely randomized factorial design.
A friction measuring device (built in Ferdowsi University of Mashhad) used to measure the friction force. It has a removable table that can move in two directions with adjustable speed. The test sample put into the vessel with internal dimensions of 300 × 150 × 25 mm and with wall thickness of 5 mm placed on trolleys. In the bottom of the container a separate aluminum plate was installed as the negative pole of the electric field. The friction plates as a positive pole placed on top of the sample. There were no contact between friction plates and walls of vessel (samples were about 2 to 3 mm higher from the edges of wall).
Frictional force changes due to movement of table, measured and recorded by an accurate load cell. From force-displacement curves, the coefficient of dynamic friction and static coefficient of friction calculated. In general, according to the experimental design, 486 tests were performed.
Results and Discussion: According to the results of statistical analysis, there is significant interaction affect between pistachios type and electrical field, as well as, the interaction between electrical field and speed, on dynamic coefficient of friction. It means two pistachio types can be separated by electrical charging.
Different physical properties of surface of filled non-splits pistachio nuts (such as corners and edges) and filled splits ones, caused differences in the distribution of electric charge and as a result, its interaction with the electric field were significant.
Changes in dynamic coefficient of friction according to the electric field intensity at different levels of moisture content and speed on the friction surfaces of iron, aluminum and rubber, was drawn in Fig.4, 5 and 6, respectively. These figures reflected the reduction of dynamic coefficient of friction by increasing the movement speed of table.
According to Fig.7, increasing the intensity of the electric field increases the dynamic coefficient of friction. Because this leads to build the opposition charge on samples and galvanized iron sheets, and with increase of electrical field, these charges will rise.
Fig.9 shows different trends of variation of dynamic coefficient of friction against moisture on rubber surface. This chart shows the higher coefficient of friction of filled non-splits samples than filled splits in all cases and shows an increasing trend with increasing humidity.
Conclusions: Table 2 presents the dynamic coefficients of friction in different states on different levels of moisture content. According to this table, the maximum difference was achieved in moisture content of 8% (which is close to the product storage moisture) in rubber surface with field strength of 7000 V and 1300 mm per minute speed. On 14 percent moisture content, the maximum difference was achieved on aluminum surface by 2500 millimeter per minute speed and 7000 V field strength. By the results, on 24 percent moisture content (the moisture close to peeling process) the maximum difference between filled non-splits and filled splits pistachios friction was achieved on aluminum surface, 7000 V electric field strength and 2500 millimeter per minute table speed.
Thus, to have a separation system, the aluminum surface, 7000 V electric field strength and adjustable speed between 1300 to 2500 mm per minute is recommended.
Research Article
E. Ahmadi; H. Barikloo
Abstract
Introduction: Some forces and impacts that occur during transporting and handling can reduce the apricot quality. Bruise damage is a major cause of fruit quality loss. Bruises occur under dynamic and static loading when stress induced in the fruit exceeds the failure stress of the fruit tissue. Needless ...
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Introduction: Some forces and impacts that occur during transporting and handling can reduce the apricot quality. Bruise damage is a major cause of fruit quality loss. Bruises occur under dynamic and static loading when stress induced in the fruit exceeds the failure stress of the fruit tissue. Needless to say that physical and mechanical properties of fruits in the design and optimization of systems related to production, processing and packaging of the products are important. Harvesting, transport, packaging and transportation of fruits and vegetables, result in their bruising which can cause loss of marketability of the fruit by consumers. The term of ‘absorbed energy’ could be used to express the quantity of damage done on the fruit and the high the absorbed energy, the higher the damage on the fruit. The object of this research was due to the importance of apricot fruit and lack of information about the mechanical behavior.
Materials and Methods: In this study, apricot fruit variety “Ziaolmolki” was examined to determine some physical and mechanical properties. In order avoid any damage, the fruits were carefully harvested from trees and gathered in plastic boxes in a row, to prevent damage to the apricots. For determination of mechanical properties and levels of impact energy used test axial machine and pendulum device, respectively. Dependent variables (acoustics stiffness, radius of curvature, color characteristic a* and b*, Brix percentage, penetration force, penetration work and penetration deformation) and independent variables (impact energy in three levels, temperature and color in 2 levels each) were selected and analyzed by block designs with factorial structure. In the experimental design, the fruits were stored in two temperature levels, 3oC and 25oC. Two areas of any fruit (red and yellow areas) were subjected to 3 impact energy levels. For each of the 8 levels, 8 fruit samples were selected. Overall, 96 fruits {8 (number of fruit per level) × 3 (impact energy level) × 2 (both red and yellow) × 2 (at 25oC and 3oC)} was selected. In this study, using a factorial experiment in a completely randomized design, the effect of different factors (impact energy in 3 levels, temperature in 2 levels 3oC and 25°C and color in 2 levels red and yellow) on acoustic stiffness, radius of curvature, color characteristic a* and b*, precent Brix, penetration force, penetration work and penetration deformation in apricot under the quasi-static forces were studied. In order to conduct this experiment, the universal testing machine of biological materials was used. After the determination of mechanical properties of the products, the SAS statistical program (1.9) was applied to analyze and normalize the resulted data.
Factorial test also was used to determine the effects of independent variables on the dependent variables. Data analyses were performed using Statistical Package for the Social Sciences (SAS version 19.0).The variance analysis of the data was conducted in the form of multivariate factorial (2×2×3) design. The data were collected by three controlling factors: two temperature levels (3 and 20°C), two types of colour (Yellow and Red fruits) and three levels of impact energy. The Duncan’s multiple range tests was used to compare the means. The values of reducible sugars were measured by the fruit juice standard - test methods No. 2685 (Institute of Standards and Industrial Research of Iran). The apricots TSS (total soluble solids) for each temperature level by Refractomete (Model: 3820 (PAL-2), Resolution: ± 0.1% Brix) were obtained.
Results and Discussion: Respectively, the main and interaction effects of these variables were examined. The results of analysis of variance showed that,, the radius of curvature, color characteristic, acoustics stiffness, elastic modulus, percent Brix, penetration force and penetration deformation on main and interaction effects were significant at 5% and 1% probability level. According to the analysis of variance table between dependent and independent parameters, a significant effect was observed. Increasing impact energy, the penetration force and penetration deformation at 3°C was higher than at 25°C (Fig.3, 4, 7 and 8). Increasing impact energy, the red zone showed more penetration deformation and penetration force than the yellow zone (Fig.5 and 6). In a constant level of energy the higher the temperature of fruit tissue, the more energy is absorbed, due to this fact that lower temperatures can increase stiffness of the fruit, and leads to transport of absorbed energy to inside the tissue and increase the fruit bruising and final results in less needed penetration force for fruit transformation. Apricot acoustic stiffness in the temperature of 3oC was higher than in the temperature 25oC (Table 3). Fruit stiffness and tissue viscosity increases with increasing temperature. With increasing tissue stiffness, the less impact energy is absorbed and less bruising in fruit tissue is created. Because of more tissue stiffness, in order to create penetration in fruit tissue the more transformation is needed.
Conclusions: The red zone showed a higher bruise susceptibility of ripe apricots. According to the analysis of variance table between dependent and independent parameters, a significant effect was observed. Increasing impact energy, the penetration force and penetration deformation at 3°C was higher than at 25°C. Increasing impact energy, the red zone showed more penetration deformation and penetration force than the yellow zone. Apricot acoustic stiffness in the temperature of 3 oC was higher than in the temperature 25oC.
Research Article
Z. Nadim; E. Ahmadi
Abstract
Introduction: The maintenance of the quality of fresh products is still a major challenge for the consumers. The most important quality attributes contributing to the marketability of fresh fruit include appearance, color, texture, flavor, nutritional value and microbial safety. Strawberry fruits should ...
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Introduction: The maintenance of the quality of fresh products is still a major challenge for the consumers. The most important quality attributes contributing to the marketability of fresh fruit include appearance, color, texture, flavor, nutritional value and microbial safety. Strawberry fruits should be firm but not crunchy. Decreased quality during postharvest handling is most often associated with water loss and decay. The postharvest life of strawberries can be extended by coating technique combined with refrigeration. Application of edible coatings is a conventional method to increase shelf life and maintain fruit quality. Edible coatings can provide an alternative to enlarge fresh fruits’ postharvest life. In this study, the effects of application of methyl cellulose edible coatings and storage time on some mechanical properties, including: the yield stress, yield strain, energy of rupture and modulus of elasticity and also, the viscoelastic behavior of the strawberry fruit was investigated.
Materials and Methods: MC (Methocel, Dow Chemical Company, Midland, MI) coating was prepared by solubilizing MC powder (3.0 g per 100 mL) in a water–ethyl alcohol mixture (2:1) at 75ºC under the high speedmixer (900 rpm) for 15 min. Coatings were used directly on the fruit surface. The physical and mechanical characteristics of fruits were analyzed on 2, 5, 8 and 11 days of storage. The puncture test and relaxation test were done using a texture analyzer (Zwick/Roell Model BT1_FR0.5TH.D14, Zwick GmbH Co., Ulm, Germany; using Xforce HP model of loadcell with capacity of 500 N, by 2 mv/v characteristic). General Maxwell model is widely used to analyze experimental results of the stress tests applied for relaxation. The obtained model coefficients were determined and evaluated from relaxation stress curves. Residues were determined using the sequential model. Usually, multicomponent models can properly describe the actual behavior of agricultural products. Results of factorial experiment in a completely randomized design were analyzed. In this study, the stress versus time graph was plotted and three-component Maxwell model coefficients were obtained.
Results and Discussion: In this current study, application of MC significantly reduced the fresh strawberries decay. Fruit decay in strawberries increased with storage time, but the coating reduced rate of decay with the length of storage. According to the results, the application of these coatings has a positive impact on yield stress and energy of rupture product texture during the storage. Average yield stress and rupture energy for the coated samples and control were 0.11, 5.71 and 0.09, 4.12 MPa respectively. The effect of treatment and storage time on the yield strain and elastic modulus were not statistically significant. The results show that provided Maxwell model satisfactorily (RMSE0.96) fits the experimental data. Also, with a retention time, the elastic component of the model is relatively reduced and the application of the coating prevents the decrease in relaxation time and improves the rheological properties of fruit. Relaxation time is different based on the characteristics of the viscoelastic or viscous substances, but this time is wider in elastic material. The relaxation time depends on the moisture content of the product, so the increase of humidity and soft, reduced relaxation time. Coatings are effective physical barrier to moisture loss and slower rates of weight loss in coated fruits because of the cover features for gas diffusion of stomata, the organelles that regulate the transpiration process and gas exchange between the fruit and the surroundings.
Conclusions: Edible films and coatings may reduce the moisture transfer, the rate of oxidation and respiration which are considered important to prolong the shelf-life of these products. This investigation showed that the MC coatings are effective for strawberries shelf life extension and retarded the senescence process in compared with control. The coat has been as a physical barrier for the gas exchange between the fruit and the environment. It was demonstrated that the coating reduced loss of firmness and delayed the softening of fruit and texture change. Fruit decay in strawberries increased with storage time, but the coating reduced rate of decay with the length of storage. Finally the results showed that coating, may increase overall acceptability, and increase the quality and shelf life of fruits.
Research Article
S. M. Mir-ahmadi; S. A. Mireei; M. Sadeghi; A. Hemmat
Abstract
Introduction: Iran is one of the main producers of kiwifruit in the world. Unfortunately, the sorting and grading of the kiwifruits are manual, which is a time consuming and labor intensive task. Due to the lack of appropriate devices for sorting and grading of kiwifruit based on the quality parameters, ...
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Introduction: Iran is one of the main producers of kiwifruit in the world. Unfortunately, the sorting and grading of the kiwifruits are manual, which is a time consuming and labor intensive task. Due to the lack of appropriate devices for sorting and grading of kiwifruit based on the quality parameters, only 10% of total production is exported (Mohammadian & Esehaghi Teymouri, 1999).
One of the main quality attribute for evaluating the kiwifruits is weight. Based on the standards, the minimum weight for an excellent kiwifruit is 90 g, while these values for the first and second classes should be 70 and 65 g, respectively (Abedini, 2003). Therefore, developing a device for fast weighing of fruits in the sorting lines can be useful in packaging, storage, exporting and distributing kiwifruit to the consumer markets.
In the past, the mechanical-based systems were commonly used for online weighing of the agricultural materials, but they did not lead to the promising accuracy and speed in sorting lines. Today, electrical instruments equipped with the precise load cells are substituted for fast weighing in the sorting lines. The dropping impact method, in which a free falling fruit drops on a load cell, is one of the suitable techniques for this purpose.
Different studies have addressed the application of dropping impact for fast weighing of agricultural materials (Rohrbach et al., 1982; Calpe et al., 2002; Gilman & Bailey, 2005; Stropek & Gołacki, 2007; Elbeltagi, 2011). The aim of this study reported here was to develop an on-line system for fast weighing of kiwifruit and compare the accuracy of different methods for extracting the weight predictive models.
Materials and Methods:
Sample selection: A total of 232 samples with the weight range of 40 to 120 g were selected. Before conducting the main experiments, the weight and dimensions of the sample were measured using a digital balance and caliper, with the precisions of 0.001 g and 0.01 mm, respectively.
Impact measuring system: The impact signals of kiwifruits in an online situation were acquired using a system, including conveying and ejecting unit, a load cell and data acquisition unit (Fig.1). The load cell was a single point load cell with 5 kg capacity. The load cell was connected to the data acquisition unit (Fig.2) in order to record the impact signal of the device in time domain of 0-5 s.
Before performing the main experiments, the load cell was calibrated using 100, 200, 500 and 1000 g standard masses. All the tests were carried out on three different forward speeds of conveyor, including 1, 1.5 and 2 m s-1 in order to obtain the optimum forward speed.
Data Analysis: In this study, two different methods were applied to build the weight predictive models. In the first method, the main components of the impact signal, including the force value at the first peak Fp, time required to peak force Dp, and the impulse or area under the first peak Ip were calculated and used as independent variables to develop the weight predictive models. In the second method, the impact components were calculated for the 40 successive peaks. Multiple linear regression (MLR) analyses were used to correlate the independent (impact components) and dependent (weight) variables.
Results and Discussion: The weight statistical characteristics of the samples, including the maximum, minimum, average, standard deviation and coefficient of variability in total data, calibration and test sets are shown in Table 1. As depicted, almost the same range and variability were observed for calibration and test data sets, indicating the proper distribution of the samples.
Table 2 summarizes the results of simple and multiple linear regressions for predicting the weight from the signal components (Fp, Dp, Ip) of the first peak at different speeds of 1, 1.5 and 2 m s-1. As shown, at the forward speeds of 1 and 2 m s-1, the multiple regression models based on all three signal components, and at forward speed of 1.5 m s-1, the model based on the combination of Fp and Ip, resulted to the best prediction powers. Among different forward speeds, the forward speed of 1 m s-1 gave the best model with SDR value of 2.180. Fig.4 depicted the predicted versus true values of weight obtained from the best linear regression models using components of Fp, Dp, Ip, Fp-Ip, and multiple of the first peak of impact signal.
The results of simple and multiple linear regression for predicting the weight from the signal components (Fp, Dp, Ip) of the first forty peaks at different speeds of 1, 1.5 and 2 m s-1 are summarized in Table 3. The best models were obtained by multiple combination of all three impact signals at the forward speed of 1 and 2 m s-1, and combination of Fpi-Ipi (i=1,...,40) at 1.5 m s-1 speed. Compared with the first peak results, the accuracy of prediction reached to 84%, 60% and 52% at forward speeds of 1, 1.5 and 2 m s-1, respectively. The best results were obtained at a forward speed of 2 m s-1, in which the SDR reached to a satisfactory value of 2.857 by applying the Ipi (i=1,...,40) values. The predicted versus true values of weight obtained from the best linear regression models using components of Fp, Dp, Ip, Fp-Ip, and multiple of the first forty peaks of impact signal are illustrated in Fig.5.
Conclusions: The results of this study revealed that among different impact component, Ip was the best predictor of the kiwifruits weight. Moreover, the developed models based on impact components of the first forty successive peaks gave the best accuracy with respect to the first peak components.
Research Article
M. Mohammad Shafie; A. Rajabipour; H. Mobli; M. Khanali
Abstract
Introduction: The pomegranate journey from orchard to supermarket is very complex and pomegranates are subjected to the variety of static and dynamic loads that could result in this damage and bruise occurring. Bruise area and bruise volume are the most important parameters to evaluate fruit damage occurred ...
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Introduction: The pomegranate journey from orchard to supermarket is very complex and pomegranates are subjected to the variety of static and dynamic loads that could result in this damage and bruise occurring. Bruise area and bruise volume are the most important parameters to evaluate fruit damage occurred in harvest and postharvest stages. The bruising is defined as damage to fruit flesh usually with no abrasion of the peel. The two different types of dynamic loading which can physically cause fruit bruising are impact and vibration. The impact and vibration loadings may occur during picking or sorting as the pomegranates are dropped into storage bins and during transportation. The focus of this work was on the impact loading as this appeared to be the most prevalent. In view of the limitations of conventional testing methods (ASTM D3332 Standard Test Methods for Mechanical Shock Fragility of Products), the method and procedure for determining dropping bruise boundary of fruit were also established by adapting free-fall dropping tests.
Materials and Methods: After the ‘Malas-e-Saveh’ pomegranates had been selected, they were numbered, and the weight and dimension of each sample were measured and recorded. Firmness in cheek region of each fruit was also measured. Fruit firmness was determined by measuring the maximum force during perforating the sample to a depth of 10 mm at a velocity of 100 mm min-1 with an 8 mm diameter cylindrical penetrometer mounted onto a STM-5 Universal Testing Machine (SANTAM, Design CO. LTD., England). Free-fall dropping tests with a series of drop heights (6, 7, 10, 15, 30 and 60 cm) were conducted on fresh ‘Malas-e-Saveh’ pomegranates. Three samples were used for each dropping height, and each sample was subjected to impact on two different positions. Before the test was started, it was necessary to control the sample's drop position. The cheek of sample was placed on the fruit holder. An aluminum plate mounted on upper part of the piezoelectric force sensor was the dropping impact surface of the device. After dropping impact, the sample was caught by hand to prevent a second impact due to sample rebound. After impact, the samples were stored at room temperature for 48h, during which time bruise tissues and arils turned brown. The bruise area and bruise volume of each sample were calculated according to equations (1 and 2).
Results and Discussion: Dropping impact acceleration versus time curves for the typical samples at ten drop heights are shown in figure 5. Drop height notably affected the impact acceleration. The peak force increased while contact times decreased with increasing drop height, which resulted in an increase of peak acceleration. Figure 6 shows the dropping impact velocity change during contact by theoretical calculation. The results showed that the velocities at the beginning of contact and the rebound velocities of the samples increased with increasing the drop height. Critical drop height of pomegranate in certain bruise area was determined and linear relationship between drop height and bruise volume for ‘Malas-e-Saveh’ pomegranates were obtained. It is clear that there were obvious differences between dropping bruise boundaries of pomegranates and the conventional damage boundary of products (as shown in figure 9). For the conventional damage boundary, the vertical line, critical velocity (Vc), represents the velocity change below which no damage occurs, regardless of the peak pulse acceleration. The horizontal line, critical acceleration (AC), represents the acceleration at which the product will be damaged if velocity exceeds VC. At the same time, for a conventional product, there is only one damage boundary at one shock condition. However, for fruit, a change in drop height (velocity) will lead to a change in bruise ratio. A series of bruise boundaries can be determined for different bruise ratios. Moreover, even if the velocity approaches zero, the fruit can still be bruised if its acceleration exceeds a certain value. These relationships provide an effective basis to predict and control drop bruising, which may be achieved through the design of reasonable cushioning packaging for fruit.
Conclusions: This research applied the concept of dropping bruise for pomegranate fruits. Because of the limitations in using conventional testing methods to test product of a viscoelastic nature, such as fruit, free fall dropping tests were adapted to determine dropping bruise fragility and bruise boundary for ‘Malas-e-Saveh’ pomegranates at different drop heights. For viscoelastic products such as fruit, even if the dropping impact velocity approached zero, the fruit could be bruised as long as the impact acceleration exceeded a certain value (critical acceleration). A series of bruise boundaries can be established for different levels of bruise ratios, i.e., a contour of constant bruise ratio can be drawn on the velocity acceleration plane.
Research Article
M. R. Bayati; A. Rajabipour; H. Mobli; A. Eyvani; F. Badii
Abstract
Introduction: Apple fruit (Mauls domestica Borkh, Rosaceae) after citrus fruits, grape and banana, is the fourth important fruit in the world and is considered the most important fruit of temperate regions. In terms of trade volume, Iran is fourth producer and 17th exporter in the world. Among Iranian ...
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Introduction: Apple fruit (Mauls domestica Borkh, Rosaceae) after citrus fruits, grape and banana, is the fourth important fruit in the world and is considered the most important fruit of temperate regions. In terms of trade volume, Iran is fourth producer and 17th exporter in the world. Among Iranian cultivars of apple fruit, known as “Golab apple”. Golab apple is one of the fragrant and tasty varieties and meanwhile is very sensitive and also its period of the postharvest shelf life is very short. In a study, the firmness of pear fruit during 4 weeks of storage was monitored using non-destructive impulse response (I-R) and destructive Magness-Taylor (M-T) puncture tests. The results of this study showed that the dominant frequency, stiffness coefficient and elasticity coefficient as a function of time could be expressed as a decreasing linear function (Gómez et al., 2005). Tiplica et al., (2010), showed that acoustic measurement can be a useful tool to discriminate different apple batches with a low error rate. Starting from the spectrum of the signal recorded by a microphone after the impact of a small hammer on the fruit, 18 key features were identified and used for the classification of apples belonging to 10 different varieties. The study aimed to evaluate apple firmness measured using both the penetrometer and acoustic methods. The methodologies were applied to Royal Gaya and Golden Smoothee apples harvested from 12 different orchards in Catalonia (Spain), on six different dates, and over three seasons. The results obtained showed a noticeable correlation between Magness Taylor firmness and acoustic measurements in Royal Gala, but no correlation was found for Golden Smoothee. In this study, also, acoustic measurements seemed to be a good tool for evaluating changes in tissue firmness during long-term storage (Molina-Delgado et al., 2009). In another study, it was presented a novel approach based on the simultaneous profiling of the mechanical and acoustic response of the flesh tissue to compression, using a texture analyzer coupled with an acoustic device. The methodology was applied to a 86 different apple cultivars, measured after two months postharvest cold storage and characterised by 16 acoustic and mechanical parameters. The results demonstrate the good performance of our combined acoustic-mechanical strategy in measuring apple crispness as it is perceived by human senses (costa et al, 2011). Hence, present study was about postharvest durability evaluation of this apple in cold storage and effect of methylcellulose coating on durability of this sensitive apple for both intact and damaged ones.
Materials and Methods: After obtaining Golab apples, from one of the gardens of Karaj (Alborz province, Iran), 240 of them were selected. Our aim in this study was to evaluate the firmness of apples with two methods: penetration (destructive) and acoustic (non destructive). The tests were performed in Agricultural Engineering Research Institute in Karaj. Firmness is one of the fruit characteristics that changes during storage. In present study, this characteristic of the apple fruit was assessed by two mentioned methods. Half of the apples were damaged with identified and controlled impact. In the next stage, another half of apples in both groups (the intact apples and the bruised apples) were coated with methylcellulose. Effect storage on apple in four groups, including: Intact and uncoated apples, intact and coated (with methylcellulose) apples, bruised and uncoated apples and bruised and coated apples during about ten weeks of cold storage at 2˚C and 85% RH was studied by the acoustic and the penetration tests. Acoustic parameters including: natural frequency, firmness index, elasticity coefficient were measured by recording audio signals resulting from non destructive impacts of a pendulum using a sound analyzer microphone and then the conversion of those parameters were performed from the time domain to the frequency domain by the corresponding formulas and software. Penetration test measurements were performed using a texture analyzer and its software. The tests were carried out every week. Statistical analysis of the results was carried out using Excel 2007 and SPSS 16 software and the significance of the results was determined using Duncan's test at the 5% confidence level.
Results and Discussion: Analysis of variance showed effect of independent variables including: effects of coating, impact and time and also interaction effects on dependent variables including: natural frequency, acoustic index and modulus of elasticity and penetration index on the tested apples. Effects of coating and time were significant at the 5% confidence levelon all dependent variables. But the impact and interaction effect were not significant on dependent variables (Table 1). In general, bruise and lack of coating on the apples during the 10 weeks of storage, were reduced acoustic parameters. In the penetration test, changes were similar to acoustic test (Table 2). In this test, all curves have downward trend and combination of independent variables: coated and intact apples were reasons of more penetration resistance of apples in all of the groups. The condition was continued until the end of storage time, despite of the downwards slopped curves in all groups. In penetration test, coated apples keep more firmness than other groups (groups of apples without coating) and thus the apple's quality would stay better, too (Fig.7).
Conclusions: In general, the following results were obtained from this research: The results showed that the acoustic and penetration parameter were decreased during 10 weeks of storage. Reduction of these parameters continued until the end of storage period, but this reduction was significant only up to eighth week. Also at this time, the acoustic parameters (natural frequency, firmness index, elasticity coefficient) and penetration firmness in intact and coated apples were 14.26%, 4.11%, 14% and 40% respectively higher compared to other apples. Due to the more tangible acoustic parameters changes, especially acoustic index and modulus of elasticity (having the more slope than the penetration firmness). One could use acoustic tests for more accurate evaluation of apples firmness and quality changes. Finding correlation between acoustic parameters and penetration parameter showed that, correlation between acoustic parameters in each case is greater than correlation between these parameters with penetration parameter.
Research Article
R. Khodabakhshian; B. Emadi
Abstract
Introduction: The economical yield of date fruits depends on many factors (Al-Shahib and Marshall, 2003). One of them is harvesting in optimum stage. Generally, date fruits have four distinct stages of ripeness to satisfy different consumption requirements (e.g., fresh and processed). They are known ...
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Introduction: The economical yield of date fruits depends on many factors (Al-Shahib and Marshall, 2003). One of them is harvesting in optimum stage. Generally, date fruits have four distinct stages of ripeness to satisfy different consumption requirements (e.g., fresh and processed). They are known throughout the world by their Arabic names which are Kimri, Khalal, Rutab and Tamr in order of ripeness (Imad and Abdul Wahab, 1995; Al-Shahib and Marshall, 2003; Sahari et al., 2007). Decreasing moisture content and increasing sugar content happens gradually while the date ripeness approaches to Tamr stage. From Kimri to Khalal stage, the size and acidity decreases when the color of Mazafati variety changes from green to red. The change in acidity continues from Rutab to Tamr stage while color transforms from brown to black. At the final stage of ripeness, Mazafati variety is soft and has a good storability (Al-Shahib and Marshall, 2003). The main Raman techniques commonly applied in agricultural product and food analyzing include dispersive Raman spectroscopy, Fourier Transform (FT), Raman spectroscopy, Surface-Enhanced Raman Spectroscopy (SERS) and Spatially Offset Raman Spectroscopy (SORS). Synytsya et al. (2003) illustrated that FT-Raman spectroscopy is a valuable tool in structural analysis of commercial citrus and sugar beet pectin. Yang and Irudayaraj (2003) employed an FT-Raman approach to detect and classify foodborne microorganisms on the whole apple surface for the first time. Schulz et al., (2005) revealed the potential of FT-Raman spectroscopy in natural carotenoid analysis. Also, many researchers have attempted to apply FT-Raman spectra on the whole fruits and vegetables. FT-Raman spectroscopy was used by Veraverbeke et al. (2005) to evaluate the natural, intact wax layers on the surface of whole fruits. Nikbakht et al. (2011) used a FT-Raman spectroscopy for qualitative and quantitative analysis of tomato ripeness parameters. The scope of this study was to evaluate the feasibility of a nondestructive method based on FT-Raman spectroscopy in distinction of Mazafati date fruits according to four mentioned ripeness stages.
Materials and Methods:
Sample preparation: Mazafati variety of date fruit was used for this study. During the harvest seasons of 2012 (July-August), the samples from each four stages of ripening namely Kimri, Khalal, Rutab and Tamr were collected from two different orchards in Bam, Kerman province, Iran. A number of 100 date samples were tested in this study, and the external features of the four stages are exemplified in Fig.1. To characterize the physical properties of studied samples, the selected physical properties such as initial moisture content, mass, geometric mean diameter, sphericity and density of studied samples were measured using represented methods by Mohsenin (1896), Jahromi et al. (2008) and Shakeri and Khodabakhshian (2011). At least, the samples were kept at 5C in a refrigerator for 7 days to distribute the moisture uniformly throughout the sample. Before spectral acquisition, the required quantities of date fruits in each ripeness stage was taken out of the frig and allowed to warm with room temperature for approximately 2 hr (Khodabakhshian et al., 2012).
Chemical properties measurements: Tissue samples were cut from each fruit separately and were macerated with a commercial juice extractor, filtered and centrifuged. The supernatant juice was used for the determination of sugar content with a manual refractometer, and expressed as percent Brix in the juice. Dry weight percentage of samples (Between 3-5 g) was determined by weighing them first, then dried them at 105ºC in a forced-air oven for 4 h and finally reweighed. PH value of date fruits was determined by a pH meter.
Raman spectroscopic set-up: FT-Raman spectra on the whole fruits in the region 200-2500 cm-1 were recorded using a Thermo Nicolet NEXUS 870 spectrometer (Thermo Electron Corp, Madison, Wis., U.S.A) equipped with a Deuterated Triglycine Sulfate (DTGS) detector and a solid substrate beam splitter. The spectra were collected with rapid scan software running under OMNIC (Nicolet, Madion, Wis., U.S.A) and a resolution of 4 cm-1 by coadding of 128 scans. FT-Raman has three main advantages over dispersive Raman systems: (1) reducing the laser-induced fluorescence that a number of samples exhibit; (2) easing the operation as with a Fourier transform infrared (FTIR) spectrometer; and (3) showing a high spectral resolution with a good wavelength accuracy (Yang and Ying, 2011). Furthermore, the Raman spectra of pure tannin were measured as a reference spectrum. The original data were used for further analysis only after subtracting dark current spectra. For obtaining dark current spectra, the laser was set to zero.
Results and Discussion:
Physical properties of date fruits: The results of some physical parameters of the studied date fruit are shown in Table1. The changes in the physical properties were dependent on the internal quality in different ripeness stages. This justification also was revealed for date fruits by Al-Hooti et al. (1995). The obtained relations between ripening stages and internal quality of studied samples are represented in the next part.
Raman spectra of tannin: Raman features of the tannin in the wavelength range of 200-2500 cm-1 are shown in Figure 3. As shown in the figure, major Raman features of the tannin were observed in the spectral region of 600-1600 cm-1. Three main Raman peaks were identified in this region. The tannin showed its highest Raman intensity at 1590 cm-1, which was higher than that at 1357 cm-1. The other peak (650 cm-1) showed low intensity. As stated by many researchers (Shahidi and Naczk, 2004; Al-Farsi et al., 2005; Biglari et al., 2008), these bands are assigned to stretching C-C, C=C and C-H bonds which compose the structure of phytochemicals. Beyond 1600 cm-1, no notable Raman scattering signals were observed. Themain Raman features of tannin were revealed in the wavelength range of 600 to 1600 cm-1 since the main Raman features of tannin are in the wavelength range of 600-1600 cm-1, this region was used for calculating the spectral information divergence to evaluate the ripeness degree of the date fruits.
Conclusions: This study reports the potential of FT Raman spectroscopy for nondestructive discriminating of Mazafati date fruits according to the four ripeness stages. The analysis of the Raman signal changes that happening during date ripening and its relationship with the ripeness degree of the date fruits was studied. In this regard, changes of pure tannin content in the wavelength range of 200-2500 cm-1 as a good ripeness index for date fruits was investigated. A modified polynomial, Self-Modeling mixture Analysis (SMA( and the Spectral Information Divergence (SID) was performed on different samples at four ripeness stages.
Research Article
E. Chavoshi; J. Amiri Parian; B. Jabbari
Abstract
Introduction: Development of science in various fields has caused change in the methods to determine geographical location. Precision farming involves new technology that provides the opportunity for farmers to change in factors such as nutrients, soil moisture available to plants, soil physical and ...
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Introduction: Development of science in various fields has caused change in the methods to determine geographical location. Precision farming involves new technology that provides the opportunity for farmers to change in factors such as nutrients, soil moisture available to plants, soil physical and chemical characteristics and other factors with the spatial resolution of less than a centimeter to several meters to monitor and evaluate. GPS receivers based on precision farming operations specified accuracies are used in the following areas: 1) monitoring of crop and soil sampling (less than one meter accuracy) 2) use of fertilizer, pesticide and seed work (less than half a meter accuracy) 3) Transplantation and row cultivation (precision of less than 4 cm) (Perez et al., 2011). In one application of GPS in agriculture, route guidance precision farming tractors in the fields was designed to reduce the transmission error that deviate from the path specified in the range of 50 to 300 mm driver informed and improved way to display (Perez et al., 2011). In another study, the system automatically guidance, based on RTK-GPS technology, precision tillage operations was used between and within the rows very close to the drip irrigation pipe and without damage to their crops at a distance of 50 mm (Abidine et al., 2004). In another study, to compare the accuracy and precision of the receivers, 5 different models of Trimble Mark GPS devices from 15 stations were mapped, the results indicated that minimum error was related to Geo XT model with an accuracy of 91 cm and maximum error was related to Pharos model with an accuracy of 5.62 m (Kindra et al., 2006).
Due to the increasing use of GPS receivers in agriculture as well as the lack of trust on the real accuracy and precision of receivers, this study aimed to compare the positioning accuracy and precision of three commonly used GPS receivers models used to specify receivers with the lowest error for precision farming operations as well as the efficiency of the work done in different situations.
Materials and Methods: In this study, three commonly used GPS models belong to GARMIN CO. were selected for comparison. This company is the world biggest manufacturer of GPS device. Three models include eTrex VISTA, MAP 60 csx and MAP 78s that in recent years have been the most widely used receivers in precision agriculture (Figure 1, Table 1). To assess the accuracy and precision of the receivers, 9 recording stations were selected in a field (20×20 m2) and detailed mapping by the odolite camera under high precision compass networks and regular conditions (figure 2) was identified. To reduce the error of multi-path, a relatively open and unobstructed place in the Abbas Abad field of Bu-Ali Sina University were considered. This study was conducted in a Completely Randomized Design (CRD) with factorial analysis to examine three factors, at three levels, each in three replication including weather conditions (clear, partially cloudy and full cloudy sky), time of day (9 am, 12 am and 4 pm) and three different models of receiver (MAP 60 csx, eTrex VISTA and MAP 78s), in 9 local stations. Difference of deviation value at each station with the mean value of latitude and longitude recorded at same station was used to precision calculate on (equation 1) and the difference of deviation value at each station with a deviation of the actual position latitude and longitude of the same station was used to calculate the accuracy (equation 2). The base station position (No.1) was determined with an accurately large-scale map. Then, the positions of other stations were defined with camera and compass in exact rectangular grid by underlying base station. Mean error for each station using equation (3) and the precision and accuracy and the definitions of each receiver was calculated.
Results and Discussion: To display the geographical distribution stations and the registered location data for GPS devices ArcView software (v3.3) was used (Fig.3). The real location of stations and registered by each receiver position has been determined. Information recorded in Map Source software, including all longitude and latitudes registered for each station and receiver were transferred to Excel Software (2007). Table 2 shows the mean precision values recorded in each weather conditions. The results obtained by equation 1 (the mean error at each station) showed that the GPS MAP 78s model has the lowest error of 91 cm, VISTA eTrex model has a maximum error of 4.7 meters and MAP 60 csx model has mean error of about 2.64 meters. The analysis of variance of models and weather conditions and the time of day with the interactions between factors have been shown in Table 3. Results showed that there is significant difference (0.01 <P value) between models, but there is no significant difference between the date and time positioning precision of different receivers models. Investigating of the interactions between the receiver models and the weather conditions showed no significant effect of them and the interaction between the receiver models and the measured time difference is not significant. These results showed that weather conditions and time of day is the same effect on positioning precision of GPS receivers used in this research. These results were consistent with the study of Jose and colleagues (Jose et al., 2006). The mean Comparison test of LSD (at 5% level) for the accuracy and precision of the models showed the significant difference for all models (Table 4). Figures 4 and 5 respectively show the accuracy and precision of three models of GPS receiver at different times of day and different weather conditions.
Conclusions: Effect of daylight hours on positioning precision was very low; also the effect of different weather conditions may reduce the accuracy of GPS positioning to size of few centimeters. Overall, the results indicated that between the three factors include the models, the effects of weather and time only receiver models had significant effect in precision. The lowest error between the models was belonged to MAP 78s (91 cm) and the maximum error was belonged to eTrex VISTA model with the 4.7 m. In addition, results of this study showed that the correct application of GPS receivers in different conditions and select of appropriate receiver can be reduced positioning error considerably. According to the result the MAP 78s GPS receiver could be used for precision farming operations in the range of 1 to 3 meter such as crop monitoring and soil sampling and the other receivers (eTrex VISTA and MAP 60 csx) could be used in operations that require less precision (range of 3 to 5 meters).
Research Article
M. Naghipour Zade Mahani; M. H. Aghkhani
Abstract
Introduction: Carrot is one of the most common vegetables used for human nutrition because of its high vitamin and fiber contents. Drying improves the product shelf life without addition of any chemical preservative and reduces both the size of package and the transport cost. Drying also aidsto reduce ...
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Introduction: Carrot is one of the most common vegetables used for human nutrition because of its high vitamin and fiber contents. Drying improves the product shelf life without addition of any chemical preservative and reduces both the size of package and the transport cost. Drying also aidsto reduce postharvest losses of fruits and vegetables especially, which can be as high as 70%. Dried carrots are used in dehydrated soups and in the form of powder in pastries and sauces. The main aim of drying agricultural products is decrease the moisture content to a level which allows safe storage over an extended period. Many fruits and vegetables can be sliced before drying.because of different tissue of a fruit or vegetable, cutting them in different direction and shape created different tissue slices. Due to drying is the exiting process of the moisture from internal tissue so different tissue slices caused different drying kinetics. Therefore, the study on effect of cutting parameters on drying is necessary.
Materials and Methods: Carrots (Daucus carota L.) were purchased from the local market (Kerman, Iran) and stored in a refrigerator at 5°C. The initial moisture contents of the Carrot samples were determined by the oven drying method. The sample was dried in an oven at 105±2°C about 24 hours. The carrots cut by 3 models blade at 3 directions. The samples were dried in an oven at 70°C. Moisture content of the carrot slices were determined by weighting of samples during drying. Volume changes because of sample shrinkage were measured by a water displacement method. Rehydration experiment was performed by immersing a weighted amount of dried samples into hot water 50 °C for 30 min.
In this study the effect of some cutting parameters was considered on carrot drying and the quality of final drying product. The tests were performed as a completely random design. The effects of carrot thickness at two levels (3 and 6 mm), blade in 3 models (flat blade, wavy blade and Ridged blade) and the cutting direction at 3 levels (linear, lateral and diagonal) were evaluated on drying kinetics, drying rate, shrinkage and rehydration. Statistic analysis done by SPSS software.
Results and Discussion: The results of analysis of variance showed that the effects of cutting parameters were significant on studied parameters (p<0.01) (Table 1). Thin layers dried faster than thick layers because of firmness of surface which it causes slow moisture transfer. The least drying time was 200 minutes at the samples that cut by a wavy blade at the lateral direction with a significant difference (p<0.05) given Fig.3. In these samples surface evaporation is more, because of more surface. The compare means showed drying rate at thick layer is fewer because of the longer distance moisture removal (Fig.6). Also the most drying rate was 0.74 gmin-1 at cutting by flat blade on linear direction with a significant difference (p<0.05).The least shrinkage was obtained on this treatment was 36.7% given Fig.8. The most of tissue of linear slices is woody part that is dense compare with other parts therefore shrinkage decrease at during drying. The most rehydration was 3.96 and 3.88 for cutting by flat blade in diagonal and linear direction with significant difference to other treatments. Rehydration depends on cell damage greatly. Since the slices of carrot that cut by flat blade were damaged fewer than other treatments therefore rehydration was more.
Conclusions: The drying behavior of carrot slices was studied at different methods in slicing carrot. The results showed a significant effect of the cutting variables on drying kinetics, drying rate, shrinkage and rehydration. The carrot moisture content decreases continuously over the drying and the fastest drying occurred at thin layers sliced by wavy blade. The slices that were cut by flat blade at linear direction caused the best quality. The results show cutting parameters are significant effect on quality of dried fruits and vegetable. There for the study of drying behavior is necessary for fruits with different tissue because of more quality of production and high efficiency at drying. Also the study of cutting parameter suggest on other fruits and vegetables with different tissue. The results help to manufactures for improvement of production of drying equipment.
Research Article
S. M. Hosseini; S. Afzalinia; K. Mollaei
Abstract
Introduction: Conservation tillage system was recommended for soil erosion control in North America for the first time 60 years ago (Wang et al., 2006). Using this tillage system including minimum and zero tillage has been rapidly developed in recent years. Thearea covered by zero tillage in 2006 was ...
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Introduction: Conservation tillage system was recommended for soil erosion control in North America for the first time 60 years ago (Wang et al., 2006). Using this tillage system including minimum and zero tillage has been rapidly developed in recent years. Thearea covered by zero tillage in 2006 was 95 million ha all over the world (Dumanski et al., 2006). In addition to saving soil and water resources, conservation tillage system reduces energy consumption and improves energy indices by combining different tillage and planting operations. Results of research conducted in Fars province shows that conservation tillage saves fuel consumption for 77% compared to the conventional system (Afzalinia et al., 2009). Conservation tillage also reduces energy consumption from 23.6 to 42.8% in comparison to the conventional tillage (Rusu, 2005). Since energy indices would be affected by reduced input energies in conservation tillage, this research was conducted to evaluate the effect of different tillage and planting methods on energy inputs and energy indices in irrigated wheat production in Eghlid region.
Materials and Methods: This research was performed to evaluate and compare the energy indices in irrigated wheat production under different tillage and planting methods. The study was conducted in the form of a randomized complete block experimental design with five treatments and three replications in Eghlid region. The treatments were included, conventional tillage and seed broadcasting (A), conventional tillage and planting with Machine Barzegar grain drill (B), reduced tillage and seeding with Roto-seeder (C), direct seeding with Jairan Sanaat grain drill (D), and direct seeding with Sfoggia direct drill (E). Experimental plots with 10 by 50 m dimensions were used in this study. Loss crop residues were taken out of the experimental plots and standing crop residues were retained in the plots. In the conventional tillage method, primary tillage was performed using a moldboard plow and secondary tillage operation was done using a disk harrow and land leveler. Seed bed was prepared in the reduced tillage method using a tine and disc cultivator which was able to complete the primary and secondary tillage operations simultaneously. Wheat seed was directly planted using direct planter without any seed bed preparation in the zero tillage method. Surface irrigation method was used to irrigate the plots and 11970 m3/ha water was consumed in each treatment. Input energies including direct energy (diesel and electricity) and indirect energy (water, labor, seed, fertilizer, chemicals, and machinery) were measured and calculated. Output energies (energy of grain and straw) were measured in each treatment and the share of each input energy, energy ratio, net energy gain, and energy productivity were determined and compared. Collected data were analyzed using SAS software and Duncan’s multiple range tests was used to compare the treatments means.
Results and Discussion: Results showed that tillage and planting methods had a significant effect on fuel and machinery energies; while, the total input energy, crop grain yield, and crop biologic yield were not affected by the tillage and planting methods (Table 4). Fertilizers and chemicals had the highest contribution in input energy of all treatments. Results also indicated that reduced tillage and seeding with Roto-seeder had the highest energy ratio (1.46) and the lowest energy ratio (1.40) was related to the conventional tillage methods (Fig.1). The highest net energy gain (47653 MJ) was obtained from the reduced tillage and seeding with Roto-seeder; while, the lowest amount of net energy gain (41388 MJ) was related to the conventional tillage and planting with Machine Barzegar grain drill (Fig.3). Results also showed that the reduced tillage and seeding with Roto-seeder had the highest energy productivity (0.115 kg MJ-1) and the conventional tillage treatments had the lowest energy productivity of 0.110 kg MJ-1 (Fig.4).
Conclusions: Results of this study showed that conservation tillage treatments (minimum and zero tillage) reduced total energy consumption (input energy) by decreasing fuel consumption and mechanical energy (energy of machinery) compared to the conventional tillage. Therefore, conservation tillage treatments had the higher energy ratio, net energy gain, and energy productivity compared to the conventional treatments. For this reason, conventional tillage and planting methods could be replaced with conservation tillage systems in Eghlid region. Meanwhile, in order to obtain more accurate results in energy indices comparison, differences in water consumption in various tillage and planting methods should be also considered.
Research Article
H. Sharifnasab; N. Abbasi
Abstract
Introduction: As a mechanical tillage practices on soil preparation improve soil structure, increase in porosity, better distribution of soil aggregates and eventually modify the physical properties of soil. The use of nano-technology in agricultural science and its application in tillage for improving ...
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Introduction: As a mechanical tillage practices on soil preparation improve soil structure, increase in porosity, better distribution of soil aggregates and eventually modify the physical properties of soil. The use of nano-technology in agricultural science and its application in tillage for improving the physical properties and mechanical issues has grown substantially.
Nanotechnology is an appropriate way to reduce soil limitations. However the nanoparticles are very small amounts in soil, due to features such as high surface area, surface charge (appearance) and sometimes porous nano-engineering of physical-chemical properties of soil are affected significantly (Mohammadi & Niazian, 2013). To use of nanomaterials in the territory of a new issue (Taipodia et al., 2011). Small developments on the use of nanoparticles to improve soil quality and land reform have been taken (Theron et al., 2008).
Clay soil was used to enhance the compressive strength (Yonekura & Miwa, 1993). Nanosilica particle effects were examined for increasing resistance against penetration and consolidation (Noll et al., 1992). In 2005, these particles were used to increase adhesion and reduce viscosity. It seemed that the adhesion of the particles was depended on Nanosilica (Mohammadi & Niazian, 2013). The use of nanomaterials showed that the increased pH and soil fertility, improved soil physical structure, and reduced mobility, availability and toxicity of heavy metals and other environmental factors and those that will stabilize the soil components and subsides the erosion in the mining pick, (Lal, 2008). In agriculture, the soil conditioner studies have shown that nanoparticles can mine the soil quality by increasing water-holding capacity, increasing silt and clay and improve levels of nutrients, and eliminate toxins, (Liu and Lal, 2012).In this study, the effect on some physical and mechanical properties of soil contain clay gradation, Atterberg limits, specifications compression and shear parameters of soil were investigated.
Materials and Methods: The study was done for 2 years at the Research Institute of Agricultural Engineering Soil Dynamics Laboratory in a completely randomized design with three replications.
Soil samples were used for different soil textures. Three types of soil texture, light, medium and heavy were considered. Nanoclay has a mineral base and can improve the properties of the soil. Two levels of the nanoclay containing zero and one percent of the nanoclay, 3 to 6 treatments in different physical and mechanical tests were repeated.
The test specimens were prepared in triplicate test and physical, mechanical and chemical testing was performed according to ASTM standard on all models. Mesh test samples were performed by sieve and hydrometer methods according to standard ASTM-D422-98.
Plastic soil properties were expressed by the Atterberg Limits, measure the ability to absorb water, soil and to a fine particle adhesion amount and type of fine particles in the soil. Psychological testing was performed to determine the extent and the paste according to ASTM-D4318-98 standard.
The maximum dry density and optimum moisture content of the soil compaction characteristics are the most important soil properties such as soil density development projects are in operation. In agricultural applications, in particular for tillage, these two factors are of particular importance. In this study, Praktor standard density testing was performed on the different treatments.
In this research, not consolidate Undrained (UU) testing methods were used. The stress tests were done at three levels 100, 200 and 300 kPa respectively.
Results and Discussion: Adding nanoparticles of clay significant impact on the size of the samples did not curve. As well as to determine the impact of nano-clay soil Plastic characteristics as psychological tests and the paste was treated on the results of these tests for different treatments and repeated ANOVA revealed a significant effect of soil type on soil Plastic characteristics. The type of control or significant influence characteristics Plastic application of nano regard.
The optimum moisture content and maximum dry density values of each sample was extracted from the respective curves that their results suggest that addition of nanoclay had a considerable impact on the density profile.
It was observed that the use of nanoparticles in soil reduced the average amount of cohesion and internal friction angle was large. This means that the increasing the nanoclay reduces the shear parameters and therefore the shear strength of the soil. This is very important in terms of tillage. Reducing the adhesion of soil particles allows the lumps are crushed with less energy.
Conclusions: Based on the results of studies and experiments conducted in this study, the following conclusions can be extracted.
- Adding nanoparticles of clay soils affect the grading curve display.
- The effect of nanoclay had more psychological impact than the same amount in the dough.
- The results showed that the addition of nanoclay had a considerable impact on the density profile.
- The use of nanoparticles in soil reduced the average amount of cohesion and internal friction angle is large.
- Due to the increase of nano-clay soil, shear strength decreased as a result of the shear parameters.
Short Paper
F. Gheshlaghi; A. Mardani
Abstract
Introduction: Rolling resistance is one of the most substantial energy losses when the wheel moves on soft soil. Rolling resistance value optimization will help to improve energy efficiency. Accurate modeling of the interaction soil-tire is an important key to this optimization and has eliminated the ...
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Introduction: Rolling resistance is one of the most substantial energy losses when the wheel moves on soft soil. Rolling resistance value optimization will help to improve energy efficiency. Accurate modeling of the interaction soil-tire is an important key to this optimization and has eliminated the need for costly field tests and has reduced the time required to test.
Rolling resistance will change because of the tire and wheel motion parameters and characteristics of the ground surface. Some tire design parameters are more important such as the tire diameter, width, tire aspect ratio, lugs form, inflation pressure and mechanical properties of tire structure. On the other hand, the soil or ground surface characteristics include soil type; moisture content and bulk density have an important role in this phenomenon. In addition, the vertical load and the wheel motion parameters such as velocity and tire slip are the other factors which impact on tire rolling resistance. According to same studies about the rolling resistance of the wheel, the wheel is significantly affected by the dynamic load.
Tire inflation pressure impacted on rolling resistance of tires that were moving on hard surfaces. Studies showed that the rolling resistance of tires with low inflation pressure (less than 100 kPa) was too high.
According to Zoz and Griss researches, increasing the tire pressure increases rolling resistance on soft soil but reduces the rolling resistance of on-road tires and tire-hard surface interaction. Based on these reports, the effect of velocity on tire rolling resistance for tractors and vehicles with low velocity (less than 5 meters per second) is usually insignificant.
According to Self and Summers studies, rolling resistance of the wheel is dramatically affected by dynamic load on the wheel.
Artificial Neural Network is one of the best computational methods capable of complex regression estimation which is an advantage of this method compared with the analytical and statistical methods.
It is expected that the neural network can more accurately predict the rolling resistance. In this study, the neural network for experimental data was trained and the relationship among some parameters of velocity, dynamic load and tire pressure and rolling resistance were evaluated.
Materials and Methods: The soil bin and single wheel tester of Biosystem Engineering Mechanics Department of Urmia University was used in this study. This soil bin has 24 m length, 2 m width and 1 m depth including a
single-wheel tester and the carrier.
Tester consists of four horizontal arms and a vertical arm to vertical load. The S-shaped load cells were employed in horizontal arms with a load capacity of 200 kg and another 500 kg in the vertical arm was embedded. The tire used in this study was a general pneumatic tire (Good year 9.5L-14, 6 ply)
In this study, artificial neural networks were used for optimizing the rolling resistance by 35 neurons, 6 inputs and 1 output choices. Comparison of neural network models according to the mean square error and correlation coefficient was used. In addition, 60% of the data on training, 20% on test and finally 20% of the credits was allocated to the validation and Output parameter of the neural network model has determined the tire rolling resistance. Finally, this study predicts the effects of changing parameters of tire pressure, vertical load and velocity on rolling resistance using a trained neural network.
Results and Discussion: Based on obtained error of Levenberg- Marquardt algorithm, neural network with 35 neurons in the hidden layer with sigmoid tangent function and one neuron in the output layer with linear actuator function were selected. The regression coefficient of tested network is 0.92 which seems acceptable, considering the complexity of the studied process. Some of the input parameters to the network are speed, pressure and vertical load which their relationship with the rolling resistance is discussed.
The results indicated that in general trend of changes, the velocity is not affected by rolling resistance. Rolling resistance increases when tire pressure decreases. This is due to energy consumption for creating deflection on the body of the tire at the lower levels of tire inflation pressure. Another variable parameter is the vertical load on the wheel and its logical relation with rolling resistance using neural network. The results showed that increasing the vertical load increases the rolling resistance.
Conclusions: The major purpose of this study was the feasibility of using learning algorithms for interaction between wheel and soil. The parameters of the wheel when clashes with soil are not stochastic and in spite of their complexity follow a specific model, certainly. Artificial neural network trained with a correlation coefficient of 0.92 relatively had a good performance in education, testing and validation parts. To validate the network results, the impact of some factors on the extraction process such as velocity, load and inflation pressure was simulated. The main objective of this article is comparing the network performance with basic principles and other scientific reports.
In this regard, the predictions by trained neural network indicated that rolling resistance is independent of the velocity of the wheel. On the other hand, rolling resistance decreases by increasing tire inflation pressure which is a general trend similar to other studies and reports in the same mechanical condition of the soil tested. Rolling resistance changes are directly proportional to load vertical variations on the wheel in terms of quantity and quality, similar to experimental models such as Wismer and Luth.
