نشریه ماشین های کشاورزی
سال یازدهم شماره 1 (پیاپی 21، بهار و تابستان 1400)

Repetitive and dangerous tasks such as harvesting and spraying have made robots usable in the greenhouses. The mechanical structure and navigation algorithm are two important parameters in the design and fabrication of mobile greenhouse robots. In this study, a four- wheel differential steering mobile robot was designed and constructed to act as a greenhouse robot. Then, the navigation of the robot at different levels and actual greenhouses was evaluated. The robot navigation algorithm was based on the path learning, so that the route was stored in the robot memory using a remote control based on the pulses transmitted from the wheels encoders; then, the robot automatically traversed the path. Robot navigation accuracy was tested at different surfaces (ceramics, concrete, dense soil and loose soil) in a straight path 20 meters long and a square path, 4×4 m. Then, robot navigation accuracy was investigated in a greenhouse. Robot movement deviation value was calculated using root mean square error (RMSE) and standard deviation (SD). The results showed that the RMSE of deviation of autonomous method from manual control method in the straight path to the length of 20 meters in ceramic, concrete, dense  soil and loose soil were 4.3, 2.8, 4.6 and 8 cm, and in the 4×4 m square route were 6.6, 5.5, 13.1 and 47.1 cm, respectively.

In this study, a model was developed for predicting the seeding rate of corn seeds of a typical row-crop planter equipped with a multi-slot feeding device. To this, nine multi-slot rotors (with 4, 5 and 6 slots in three angles of mouth including 23°, 25° and 27°) were designed and manufactured. Tests were carried out at four levels of angular velocity of 40, 52, 62 and 78 rpm on grease belt moving at constant speed of 3.5 km h-1. Tests were completed in three replications. Discharge flow rate was measured and recorded for each treatment. The data were used to develop a model which can be used for predicting the seeding rate under various numbers of slot, mouth angle and rotor angular velocity. According to the results, angle mouth of slots, number of slots, angular velocity and the dual interaction between them showed increasing effects on weight flow rate of seeds (P-value<0.01). In the next step, raw data were used to develop the two desired models: based on the dimensional analysis technique and response surface methodology (RSM). The models outputs were compared to experimental data. The standard error of estimate for flow rate for dimensional analysis and response surface methodology (RSM) were 68.13 mm3 s-1 and 475.59 mm3 s-1, respectively. The dimensional analysis model was closer to experimental data rather than the RSM method. Thus, to predict the volume flow rate of seed, the dimensional analysis model is recommended.

Several histogram equalization methods for enhancing the color images of Rosa Damascena flowers and some thresholding methods for segmentation of the flowers were examined. Images were taken outdoors at different times of day and light conditions. A factorial experiment in the form of a Completely Randomized Design with two factors of histogram equalization method at 8 levels and thresholding method at 15 levels, was implemented. Histogram equalization methods included: CHE, BBHE, BHEPL-D, DQHEPL, DSIHE, RMSHE, RSIHE, and no histogram equalization (NHE) as the control. Thresholding method levels were: Huang, Intermodes, Isodata, Li, maximum entropy, mean, minimum, moments, Otsu, percentile, Renyi’s entropy, Shanbhag, Yen, constant, and global basic thresholding method. The effect of these factors on the properties of the segmented images such as the Percentage of Incorrectly Segmented Area (PISA), Percentage of Overlapping Area (POA), Percentage of Undetected Area (PUA), and Percentage of Detected Flowers (PDF) was investigated. Results of histogram equalization analysis showed that DQHEPL and NHE have the statistically significant lowest PUA (11.13% and 8.32%, respectively), highest POA (89.35% and 92.07%, respectively), and highest PDF (61.88% and 64.94%, respectively). Thresholding methods had a significant effect on PISA, PUA, POA, and PDF. The highest PDF belonged to constant, minimum, and Intermodes (75.07%, 73.08% and 74.30%, respectively) They also had the lowest PISA (0.35%, 1.29%, and 1.85%, respectively) and PUA (33.72%, 23.09%, and 15.56%, respectively). These methods had the highest POA (80.73%, 76.70%, and 84.67%, respectively). Hence, they are suitable methods for segmentation of Rosa Damascena flowers in color images.

The agricultural sector is in need of a rapid transition from traditional and livelihoods to the stage of advanced production and commercialization, in order to provide food security for the community and to play an effective role in strengthening national independence. Mechanization is an approach that allows the agricultural sector to achieve the stage of commercial production. Without mechanization, there is no clear vision of a dynamic and sustainable agriculture that can rectify the food needs sensibly. The development of mechanization in agricultural societies, especially in the rural areas, has been accompanied by problems that the identification of the factors affecting it can help plan to eliminate them. Therefore, in the present study, the effect of the fragmentation of land on the development of agricultural mechanization in the rural districts has been investigated. The research type is applied and descriptive-analytic, survey method has been used and information has been collected through a questionnaire from 420 users in Jiroft city. The data were analyzed using a hierarchical analytical process technique using Expert Choice11 software. The research findings show that the family-social factor in the city of Jiroft was the main deterrent to the lack of development of mechanization and the cultural-communication, educational-technical, lawful-legal, and economic-financial factors were placed in the next priorities. It is proposed to implement the development of mechanization, the modernization of modern technology, education and promotion, building trust, credit and financial facilities for the modernization of agricultural implements.

Pomegranate seed oil (PSO) is a well-known source of valuable compounds. The aim of this study was to investigate physicomechanical and structural properties of jelly candy enriched with PSO encapsulated in chitosan (CS)-capric acid (CA) nanogel incorporating thyme essentioal oil (TEO). For this purpose, initially the CS-CA nanogels were produced by creating amide bondes between CS and CA, which Scanning Electron Microscope (SEM) image showed the spherical form of CS-CA nanogels. Then, PSO-in-water Pickering emulsions were stabilized with the CS-CA nanogels as well as the CS-CA nanogels incorporating TEO. The results showed that the presence of TEO in the nanogel structure caused smaller oil droplets. Then, Pickering emulsions were used in the formulation of jelly candy and subsequently the microscopic structure, texture profile analysis (TPA) and color indexes of jelly candies were studied. The use of PSO in the encapsulated form reduced the separation of the PSO from the texture of the jelly candy. The results of TPA showed that although the samples containing PSO in the encapsulated form had lower hardness (156.6-173.4 N), gumminess (202.2-262.1 N), cohesiveness (1.3-1.5%), resilience (40.2-54.7 N.s) and adhesiveness (0.29-0.4 N.s) than the control (250.3 N, 627.9 N, 2.14%, 160.7 N.s, 0.63 N.s), their springiness (0.92-0.93%) was higher than the control (0.79%). Moreover, the color indexes showed that the samples containing PSO in the encapsulated form changed the color indexes more than the control, which was more in the presence of TEO.

Nowadays, the dielectric properties of food and biological products have become a valuable parameter in foodstuff engineering and coating technology, covering a remarkable spectral domain from 10-6 to 1012. In the present study, 27 completely healthy pears were selected and subjected to quasi-static and dynamic loading. The storage period was ten days. In this study, the qualitative characteristics and their relationship with changes in dielectric coefficient were investigated. At the end of the storage period, the fruits’ dielectric coefficient values and their qualitative characteristics were measured. The measurements were carried out for a capacitor plates’ distance interval of 11 cm, 10 V input voltage and 60 kHz input voltage frequency. According to the results, in the dynamic loading mode of 400 N, the highest dielectric coefficient with a value of 5.2989 was obtained. In dynamic loading mode of 400 N, the qualitative property had the minimum value. The antioxidant, phenol content, Vitamin C content and firmness were 33.925%, 14.523 mg/100g, 5.7 mg/100g and 5.5333 g, respectively. The results of the study indicated that increasing the loading force on the pear reduces all qualitative indicators for all loading modes and an increase in dielectric coefficients of the products was observed.

In this research, an attempt was made to utilize an Earth-Air Heat Exchanger (EAHE) system as a source of shallow geothermal energy to provide thermal demands of a commercial greenhouse located in Alborz province, Iran. The degree-day index was applied to estimate the EAHE system’s potential to meet the thermal requirements of the greenhouse including cooling and heating demands. The results indicated that this region needed more energy to reach to the relevant temperature inside the greenhouse for the heating demand comparing to the cooling one. The average potential of the EAHE system based on the degree-day index was 10.76ºC for increasing temperature in the cold and 17.96ºC for decreasing temperature in the warm season. This means that the EAHE system was capable of supplying the greenhouse thermal demands in this area according to the calculated values of Heating Degree-Day (HDD) and Cooling Degree-Day (CDD). This method would be beneficial in monitoring and optimizing plant growth conditions as the best crop type or cultivation selection which in turn can help in irrigation and fertigation management of the crop grown.

The aim of this study was to investigate the energy consumption and production costs of sweet-cherry and sour-cherry in Northeastern Iran. Required data were collected from 75 sweet-cherry and 42 sour-cherry producers. The total energy inputs in sweet-cherry and sour-cherry production were estimated as 37.76 and 31.03 GJha-1, respectively. The energy efficiency of sweet-cherry production was greater than sour-cherry production. Chemical fertilizers and diesel fuel were the most highly consumed energies in both crops. The higher share of non-renewable energies consumed to produce sweet-cherry than sour-cherry revealed that sweet-cherry production was more dependent on non-renewable sources compared with the sour-cherry production. The economic analysis revealed that production costs for sweet-cherry were higher than sour-cherry but sweet-cherry was more profitable than sour-cherry because of premium prices for sweet-cherry. The modeling results showed that the human labor input had the most impact on costs of both crops. As a consequence, the main practical solutions could be saving in diesel fuel and fertilizer management, which could more properly overcome economic and energy problems in the two crops.

Contamination due to hydraulic fluids exerts deleterious effects after a long time, however this factor is often ignored or its consecutive breakdowns and system failures are considered due to other factors. Therefore, in order to prevent the likelihood of occurring such problems, the following two strategies are presented: using oil change method to replace all of the hydraulic fluids from the discharge system with the new oil and using offline hydraulic oil filtration system for the removal of contaminated oil particles. In this regard, the present study aimed to investigate the economic status of cane sugar harvesting machines with an emphasis on hydraulic oil filtration process in seven units of sugarcane developmental company and affiliated industries in Khuzestan province, Iran. To perform this study, all statistics and data of the sugarcane and affiliated industries in seven companies during the crop year 2011-2016 were collected and classified. The results indicated that the application of the hydraulic filtration method led to the oil consumption saving (per liter) and in price (Iranian Rial) during the three crop-years of 2014-2016, as following: Imam Khomeini: 25500 L and 2882154363 Rials, Amir Kabir: 49000 L and 5847389466 Rials, Hakim Farabi: 82000 L and 9534396744 Rials, Dabal Khazaee: 73400 L and 6808230362 Rials, Dehkhoda: 31680 L and 3421979639 Rials, Salman Farsi: 73500 L and 7606675370 Rials and Mirza Koochak Khan: 75934 L and 8083068395 Rials

Abstract This study deals with the application of the Microsoft Excel for the estimation of the power requirements of some tillage implements. The mathematical formulas embedded in the spreadsheet file have been developed in the previously published papers; however, those formulas were augmented herein in order to contain some agricultural mechanization issues. Another feature of this article is the ability of the spreadsheet to generate trend curves automatically. The comparison of the power expenditure aspects of different tillage implements as well as the inspection of the effect of an arbitrary selected input parameter on the spreadsheet outputs were effectively performed. Numerically, the specific work of the rotary tiller was estimated two times to five times higher than the specific work of drawing implements. Furthermore, as an example of trend curves derived in this article, the increase in disc angle in the range of 25° to 70° reduced the draft and power needs of the disc plow by 66% and 54%, respectively. However, it increased the disc plow specific draft and power by 34% and21%, respectively.