مجله پژوهش های مکانیک ماشین های کشاورزی
سال دوازدهم شماره 2 (تابستان 1402)

One of the effective ways to reduce agricultural operations as well as production costs is to use cobined machines. In this study a seed-fertilizer drill has been combined with a heavy disk and evaluated in field condition and compared with other reduced and no till methods. Main plots were four tillage-planting methods included of: designed combine machine (T1), no tillage with direct drill (T2), two pass disk fallowing with grain drill (T3), chisel packer fallowing with grain drill (T4). Subplots were seed rated at three levels included of: 150, 175 and 200 kg/ha. The results show that treatments were significantly different from view point of technical indices however they were not significantly different from view point of agronomy indices except Percentage of Emergence Percentage of Emergence. The highest and lowest rates of fuel consumotion assigned to T4 and T1 with 38.4 and 14.5 l/ha, respectively. Also T1 tretment fallowed by T2 treatmet had the second grade in field capacity with 1.66 ha/h rate. The combined machine could save in operation time and fuel consumtion related to T4 with 17.6% and 62.2% rates, respectively. The results of evaluation of seed rates showed that seed rates upper than 150 kg/ha didn,t have significant difference from view point of agronomy indices exceot to spike numbers per m2. According to these results, this combined machine (fertilizer -seeder equiped with heavy disk harrow) is suitable for conservation tillage and seeding of wheat.

Iran is one of the world's largest and most important raisin-producing countries. Considering the amount and value of raisin exports in Iran, mechanizing this product's collection and maintaining its mechanical quality is one of the most necessary tasks in this field. Therefore, the main purpose of this study is to design and construct a collection head in a Rover for collecting raisin products from the ground and then evaluate the mechanical damage of raisin crops during collection from the ground by the collecting head. After performing the software design, the necessary calculations were performed to select different device parts. The rover was evaluated on raisins spread on the ground at three forward speeds of the rover (1, 2 and 3 km/h) and three heights of the head (2, 5 and 10 mm) from the ground surface. The constructed head with a length of 80 cm was mounted on a rover with dimensions of approximately 70 × 50 cm. The working capacity of this machine at the rotational speed of 25 rpm of the collecting brush is equal to 3.3 kg/min, and it is able to fill the 80 kg container every 15 minutes. The evaluation results showed that the effect of forward speed and head height on mechanical damage was significant (p <0.01), but their interaction was not significant. Also, the lowest mechanical damage (11%) was related to the height of 2 mm from the ground. Mechanical damage of the product was reduced by 8% at the forward speed of 1 km/h compared to the other two speeds.

This study investigates the life cycle assessment of cucumber greenhouse production in four cities, Karaj, Hashtgerd, Nazarabad, and Eshtehard, during the crop year 2016-2017, using three energy production systems: conventional (using electricity from fossil fuel sources and diesel for greenhouse heating), photovoltaic, and photovoltaic-thermal. The equivalent amounts of energy consumption were calculated and simulated using TRNSYS software to determine the fuel and electricity requirements of the photovoltaic and photovoltaic-thermal systems. In the next step, IMPACT2002+ method was used to investigate the pollution incidence in the scenarios for cucumber production. The results of life cycle assessments showed that in all photovoltaic system damage categories, the emissions were the least. In addition, the results showed that the total emissions were the highest in the conventional system, followed by the photovoltaic thermal system in the next well. Simulation of solar systems also showed the maximum number of panels needed for photovoltaic and photovoltaic-thermal systems in greenhouse production of 160 and 159 in order to cultivate one ha of cucumber greenhouse production. The life cycle assessment results showed that in all damage categories of the photovoltaic solar system, it has the lowest emission. Also, in the three systems, diesel fuel, photovoltaic and photovoltaic-thermal systems and in parallel with in-field emissions, have the highest share in the injury category emissions. The results showed that the highest level of damage categories, include of human health and ecosystem quality, are 0.005 DALY and 9215 PDF*m2*yr, respectively, in the scenario of energy production using the photovoltaic system and in the damage categories, include of climate change and resource amount of 6629 kg CO2 eq. and 145446 MJ primary were obtained using the conventional energy production system. Results showed that the photovoltaic solar system was the best scenario in all three scenarios.

The aim of this study was a three-dimensional simulation of the heat and moisture transfer process in food drying operations. A three-dimensional geometric model of carrot slices was used for simulation. The domain was discretized into 1017 tetrahedral elements, with a freedom degree of 30550. Governing differential equations of heat transfer and moisture transfer during the carrot drying process were solved under different drying air temperatures based on the finite element method using the Comsol Multiphysics 3.5 software. The equation was solved by considering the variable engineering properties of carrots. The temperature and moisture profiles were predicted at different drying conditions. In addition, some experiments were performed to obtain the engineering properties of carrot slices, such as bulk and true density and the effective moisture diffusion coefficient during hot air drying at different thicknesses of slices and air temperatures. The predicted data were compared with the experimental data. Results showed that the model can accurately predict the moisture and temperature variation of the sample during the drying process. Prediction accuracy was 99.87 to 99.98 %, and the error was 3.5 to 19 %. Therefore, the developed simulator can be highly accurate for other agricultural products with similar engineering properties

Considering that wheat and barley are important and strategic products in Iran, the Sunn pest is one of the most important pests of these products. Every year, the country's plant protection organization monitors this dangerous pest so that an order to fight it can be issued at the right time. Farm monitoring is a very difficult, time-consuming, and destructive task; it also requires a large number of specialized human resources. One of the goals of this research is to create a non-destructive method for such an operation in the identification of Sunn pests. In this research, the counting of Sunn pests in cereal farms was done by two methods using aerial image processing by recording 954 images and framing method and eye counting in the farm by an expert in two farms with different numbers of this pest. The number of pests in each image was obtained after processing the images using the Python programming language in the PyCharm learning library. The statistical study results showed no significant difference at the 1% probability level between the average data of the two methods. This method can be used confidently to monitor the Sunn pest in cereal farms. In this research, by using UAV image processing, a fast, accurate, and non-destructive method was proposed and evaluated for counting the pests and issuing spraying orders in cereal farms.

The current research used a hybrid conveyor belt drying system, including a solar water heater and solar-powered infrared lamps, to dry rosemary leaves. Its performance characteristics were evaluated regarding drying time, total energy consumption, solar energy ratio and energy efficiency. In each experiment, 300 g of freshly harvested rosemary leaves at a drying air temperature of 50 °C and different values of inlet air velocity (7, 8 and 9 m/s) and infrared lamp power (0, 150 and 300 W) were fed into in the drying system. The optimum point for the working of the drying system was determined using Response Surface Method (RSM) by selecting the appropriate values for the inlet air velocity and infrared power based on these criteria: to minimize drying time, to minimize total energy consumption, to maximize energy efficiency, and to maximize solar energy ratio. Accordingly, the selected optimum point included infrared power of 300 W and an air velocity of 8.85 m/s. Under the defined conditions, the performance characteristics of the drying system, including drying time, total energy consumption, energy efficiency and solar ratio, were equal to 149.13 minutes, 3868.91 kJ, 52.37% and 0.75, respectively. According to the findings of this study, it can be concluded that using a developed drying system can significantly reduce the need for fossil fuel resources and lead to an acceptable performance efficiency in the drying process of medical plants.

Connecting the tractor engine to its front axle and maintaining the Wheel-Base (WB) distance of the tractor in its standard range is done using a part called the front bracket. It's part of the tractor's main chassis. This study was carried out to manufacture a new bracket due to the increase in engine power of a tractor from 37 to 52 kW. The WB distance of a tractor directly depends on its engine power. The bracket was designed in three-dimensional form by Catia software and analyzed in terms of mechanical strength by finite element method under static and dynamic loads in Abaqus software. Due to the need for high strength in this part, ductile cast iron (GGG40, yield strength: 250 MPa) was considered as its raw material. Static and dynamic analysis results showed that the maximum stress applied to the part (93.7 MPa) is lower than the yield strength of the designed part. Once the part's strength was verified, a casting mold was designed using Catia software and manufactured by aluminium casting and machining. Five initial samples were then cast and machined before being installed on sample tractors (RK704 model, maximum weight: 2635 kg) for field tests. The results of the tests indicated that the manufactured part maintained the WB distance, installation conditions, and mechanical strength and was reliable for use in producing this tractor.

The compaction of agricultural soils is the main limitation to crop roots, leading to reduced yields for most agronomic crops. Soil compaction alters soil structure and limits water and air infiltration. The vertical penetrometer is commonly used to measure soil resistance, but it is time-consuming, costly, and challenging, which has limited its use in soil compaction mapping in vast fields. One of the methods introduced in the last decades is a continuous and on-the-go system to determine the compacted soil layer. This study aimed to measure the mechanical strength of soil at different soil depths using an on-the-go horizontal pneumatic sensor designed and fabricated. The stress calculations for the tine were performed first, followed by a stress analysis of the proposed tine stem using ANSYS software. Then, three conical nozzles at three depths (15, 30, and 45cm) were installed on the pneumatic sensor tine to inject airflow into the soil, and three pressure gauges measured the resistance to air permeability into the soil. The sensor was tested and compared with the standard vertical penetrometer in three replications. The comparison results specified that the sensor could show different soil compactions at various depths, even where a vertical penetrometer could not penetrate the soil. There was a significant relationship between the mechanical strength of soil and vertical penetration resistance (R2=0.73) at depths of 0-30cm. The air permeability resistance in the soil increased with the soil depth.

Foodstuff adulteration involves replacing expensive ingredients with low-cost substances to decrease the production cost and reach the maximum profit. In recent years, the issue of food adulteration has reached an alarming stage. The detection methods currently available for this problem are often costly, time-consuming, and require high technical expertise. Lemon juice has repeatedly been the victim of fraud attempts by manufacturers to lower the price of products. Electronic noses are used in many fields, including the beverage industry, for classification and quality control. The process involves detecting and differentiating volatile organic compounds (VOCs) released from food. This study used an electronic nose equipped with 8 metal oxide sensors to evaluate pure lemon juice and 11 counterfeit samples (water, lemon pulp, and wheat straw) to detect fraud through VOC analysis. The response patterns of the sensors were analyzed using chemometric methods, specifically Quadratic Discriminant Analysis (QDA) and Mixture Discriminant Analysis (MDA). According to the results obtained from the QDA and MDA methods, the total variance was 100% and 98.89%, respectively, for the classification of samples. Hence, it can be concluded that the electronic nose based on metal oxide semiconductor sensors combined with chemometric methods can be an effective tool with high efficiency for rapid and non-destructive classification of pure lemon juice and its counterfeits.

Orange is one of the most important citrus species in the economy and industry. This study aimed to dry the oranges with a combined pretreatment of osmotic solution and ultrasound waves to reduce the drying time and improve the quality of the dried product. In this study, a hot air dryer was used to investigate and optimize drying time, water reabsorption capacity of dried samples and shrinkage index of dried samples of orange slices. The samples were pretreated by immersing them in an osmotic solution with brix at three levels of 15, 30 and 45 degrees and applying ultrasonic waves to the samples at three-time levels of 10, 20 and 30 min in the ultrasonic bath. The pretreated samples were dried at three temperature levels of 70, 80 and 90℃ and three hot air velocities of 1, 1.5 and 2 m/s. The results showed that by increasing the concentration of an osmotic solution from 15 to 45 and increasing the ultrasonic time from 10 min to 30 min, the total drying time and the shrinkage index of the product decreased. The water reabsorption of the dried samples was dependent on the variables of ultrasonic time and osmotic solution concentration (P<0.01). The best state of water reabsorption, which was 8.9, occurred at 15° Brix and 30 min of ultrasound. The optimization results showed that the optimal point with the highest desirability index (0.808) occurred at 45° Brix of the osmotic solution, 30 min of ultrasound, 70°C and 1.07 m/s of hot air dryer.