نشریه مکانیزاسیون کشاورزی
سال هفتم شماره 2 (تابستان 1401)

AbstractIn many date palm gardens, different varieties of date fruits are commonly grown. Each of these varieties has different physical and chemical properties. Therefore, in the first step of developing intelligent sorting systems and quality monitoring systems, it is highly desirable to develop an automatic method for identifying the type of date fruit variety. This study aims to develop a classification algorithm of date fruit varieties using electronic responses from capacitive sensors and a force transducer. To simultaneously obtain the capacitive properties including the frequency and analog responses of date fruit and the force parameter related to the weight of the date fruit, an electronic platform was designed and constructed. In this platform, the capacitive responses and force parameters were provided by setting up the IC 555 and calibrating a 1 kg load cell. 120 date fruits from four different varieties, including Zahedi, Qhasb, Mazafati and Medjool were considered for the model development. A total of 30% of the samples were separated for final classification evaluation.  Decision Tree (DTs) as a non-parametric supervised learning method was chosen for classification. To tune, the classification model with the best hyper parameters fitting 3 folds for each of 2204 candidates, totaling 6612 fits were examined. The evaluation of the developed model resulted in a classification quality with F-scores of 64%, 50%, 100% and 100% for the four varieties Zahedi, Qhasb, Mazafati and Medjool. It was concluded that the developed capacitance base classification system can be successfully used to classify date fruit with acceptable quality.

Pneumatic precision seeders are used for sowing of cereals. However, sowing small uncoated seed of medical plants is very difficult by these seeders. The purpose of this study was to investigate the performance of the pneumatic cylinder distributor to sow uncoated thyme seed and to determine its optimal conditions. The effects of four factors were investigated: the suction pressure at -6, -8, -10 kPa, the linear velocity of distributor at 3, 4, 5*10-2 m. s-1, the diameter of the distributor hole at 5, 7*10-4 m and the seed hole shape in conical and straightforward forms. In order to estimate the distributor yield, three indices of miss index, multiple index and quality of feed index for thyme were examined. The experiments were performed in 5 replications by the factorial method in a completely randomized design. The results showed that the suction pressure and linear speed of the distributor had a significant effect on the indices. The best performance of the distributor unit was obtained at -10 kPa pressure, 3*10-2 m. s-1 linear speed of the distributor, 7*10-4 m diameter for the distributor hole and the shape of the conical hole. Under these conditions, the values of miss, multiple and quality of feed indices resulted in 0.4%, 4.4%, and 95.2%, respectively.

Most farmers perceive that moldboard ploughing prior to potato planting is necessary, despite its negative impacts on inherent soil fertility and soil structure. Conservation tillage may be an alternative system for potato production due to its potential to reduce production costs and soil conservation. Many studies have investigated the effect of different tillage methods on various factors such as soil physical properties, costs and yield in potato cultivation. Most of the studies only cover a small range of field experiments, in a region. In order to gain a better perspective on the impact of tillage methods on potato yield, available studies were systematically reviewed and their findings were analyzed by meta-analysis (1966-2021). All articles published in journals, final reports of research projects and related articles presented at congresses, as well as student dissertations were reviewed using standard keywords. Finally, after quality control, 25 studies (5 national studies and 20 international studies) were entered into the meta-analysis process to compare the method of minimum tillage with conventional tillage using a random model. The results showed that the minimum tillage method (chisel ploughing conducted in the spring immediately before potato planting) compared to conventional tillage (moldboard ploughing) caused a slight increase in potato yield (+ 0.13%). It is suggested that the reduced tillage method (plowing with a chisel plow in the spring before planting + disc) replaces the conventional tillage method (moldboard plow + disc + leveler).

Tillage is one of the most important field operations in agriculture. For this operation, it is essential to determine suitable working conditions. According to the results of researches on tillage, this operation is always associated with high energy consumption. For this reason, it is necessary to choose the appropriate forward speed and plowing depth of tillage tools in terms of optimal energy consumption. In this research, by using the management method TOPSIS, the appropriate speed-advancement and plowing depth have been investigated according to the parameters of energy consumption. In this research, three types of primary tillage machines (Moldboard plow, disc plow and chisel plow) at 3 different forward speeds (3, 4.5, 6 km/h) and different depths (15, 20 and 25 cm) was selected and performed in loamy clay soil with a moisture content of 7%. The parameters of energy consumption include drawbar power (kW), fuel consumption (l.ha-1), traction efficiency (%) and energy efficiency (OEE) (%), mechanization capacity (kW.h.ha-1) and specific traction (kN.m-1) was measured. The results showed that for the moldboard plow and disc plow 4.5 km/h forward speed and 25 cm depth and for the chisel plow, 6 km/h forward speed and 15 cm depth were the best conditions in terms of energy consumption. In most of different working speeds and depths, chisel plow was advantageous in terms of energy consumption, compared to disc plow and Moldboard plow, according to TOPSIS analyses.

Potato ranks 4th in terms of production volume among various agricultural products after wheat, rice and corn. Potato planters, usually plant seed potatoes at a constant distance regardless of their size which leads to a heterogeneous distribution of stems at field. The main aim of this research was to design, develop and evaluate a special potato belt metering device. Belt planters use a group of belts to receive, deliver and plant potatoes. In this type of planters, the potatoes first fall from the hopper onto the middle of the planting belts. Return belts move in the opposite direction and guide the extra potatoes to the beginning of the path to be used for reloading by the middle belts. In this study, the evaluation of the metering device was performed in the laboratory with the use of a test rig. A factorial experiment conducted in a completely randomized design with 3 replicates to investigate the effect of the forward speed of planting belts and test rig, potato sizes and potato shapes on the mean planting distance, standard deviation, multiple planting index, miss and quality of feed indices and the accuracy. Results indicated that the mean seed spacing, standard deviation, multiple planting index, miss and quality of feed indices were significantly depend on the planting belts and test rigs forward speeds, potato size and shape. With the increase in the forward speed of the test rig, the mean seed spacing and miss index increased by 4.21 and 17.69%, respectively , while the amount of reduction in the feeding quality and multiple planting index were equal to 7.78 and 10%, respectively.

Tree structures are complex and random in nature but they follow some specific rules according to their various kinds. The objective of this work is to model three fractal trees’ dynamic behavior in the mechanical shaking process and study the effect of the bifurcation ratio and the length-order ratio (pruning ratio) on the frequency response and the percentage of the harvested fruit. Experimentally the static loadings are carried out on the trunk and branches of the tree to obtain their important elastic properties. In order to obtain viscoelastic properties of the tree, its dynamic free vibration is examined. The fractal trees are modeled with an equivalent multi degree of freedom mass-spring models and the governing equations of motion are derived by means of Newton’s second law; then, they are solved numerically for some sample fractal trees. Consequently, for different values of the bifurcation ratio and the length-order ratio (fractal dimension), the displacement of the fruit is calculated and the displacement amplitude of the fruit is obtained. Also, the effects of the tree structures and pruning ratios on the displacement amplitude of the fruit are discussed.