نشریه مکانیزاسیون کشاورزی
سال ششم شماره 2 (تابستان 1400)

 By depletion of fossil fuel resources in the world, the need for the new resources in the various field and among them in agriculture has raised. The use of biodiesel as a renewable, non-poison and eco-friendly fuel is a significant solution in this area. In this relation, evaluating the performance characteristics of biodiesel has vital importance. In this research, the experiments were performed using 0, 10, 20 and 30% biodiesel mixed with diesel in a sub-scale tank for evaluating the mixture performance in tractor traction. Diesel fuel was used as the basis for comparisons. The experiments were performance in three tillage depths of 20, 25 and 30 cm, and in three forward speeds of 1.8, 3.6 and 5.4 km/h. For drawbar force measurement an octagonal ring drawbar dynamometer and for real speed a radar were used. The tests were performed in the factorial completely randomized design. The different fuel factors effect were measured on tractor performance parameters (real speed, drawbar force, slip, traction power) in a soilbin. Analyses of variances for the experiments showed that the real speed, slip, drawbar power, traction force and their interaction effects were significant at 5% and 1% of probability level. Adding biodiesel for tractor fuel increased the values for drawbar force and drawbar power.

 In this research, some parameters affecting walnut kernel extraction quality under impact loading were studied. The tests were carried out on the available genotypes in Iran. For this purpose, three different genotypes from walnut orchards of Azarshar city were selected and the total yield of these genotypes was collected. The universal test machine (Hounsfield) was used for the compression tests. For the impact tests, four factors were evaluated in a factorial experiment using a completely randomized design with five replications. The factors were genotype, moisture content, load direction with three levels, and compression speed (three levels), and the effect of these factors on kernel extraction quality was studied. Walnut breakage assessments and kernel extraction quality were evaluated by well-defined criteria. Generally, with increasing moisture content, the percentage of broken kernels decreased and the extraction quality grade was improved. The percentages of broken kernels increased when compression speed was increased. Generally, soaking the walnuts in water for 12 h and Y loading direction yielded the best kernel extraction quality.

Selection of appropriate tractor as the source of power in farms is one of the most important decisions in farm management and a main task for farm managers and farmers. The main goal of this study was to select the best tractor in Saral region of Dyvandara County. Different criteria were used for selecting of an appropriate tractor such as power, safety, reparability, maneuverability, price, accessing to repair service, movement speed, power proportion to farm size, fitting the price and costs of tractor with the size of farms and the farmer's income. The statistical population for evaluating the tractors was 40 experienced operators and farmers  selected randomly. Data and value were analyzed and evaluated using the multi-criteria method. The results showed that safety and transport ability and price are the most important factors in the selecting a tractor in this region. According to the results, the medium range ITM 285 was the best tractor. Also, results showed that semi-heavy and heavy tractors were not suitable for this region with small size farms area. The results showed that non-agricultural use of tractors has a significant effect on the importance of a criteria for selecting suitable tractor in Saral region.

The essential oils of medicinal plants are evaluated and used in the pharmaceutical and food industry based on the amount of active ingredients in them. One of the effective methods for identifying and evaluating essential oils is the electronic nose, which has fewer weaknesses than conventional methods. In this study, an electronic nose system consisting of 8 metal oxide semiconductor sensors was designed to determine the purity of peppermint essential oil. The PCA method was used to reduce the size of the data and identify effective sensors, and the artificial neural network method was used to calculate the accuracy of data classification. Based on the results, the principal component analysis method with two main components PC1 and PC2 was able to explain 82% of the variance of the data. Sensors that had a greater impact on the separation of essential oil purity classes were also identified. The accuracy of data classification in the training and testing stages in the artificial neural network method was 81% and 70%, respectively. Therefore, the proposed electronic nose system based on the mentioned algorithm is a reliable and low-cost tool for qualitative grading of different samples of purity of peppermint essential oil from each other.

Common planters in dryland conditions are planters that equipped with presses wheel that are suitable for planting in dry conditions. But the same press wheel in spring planting, such as dryland chickpeas in late March in cold areas where soil moisture is high, cause soil compaction and reduced yield. On the other hand, harvesting by hand is difficult and also in the preparation of land for planting wheat, the appearance of large lumps makes planting difficult. Therefore, hence due to the lack of access to a suitable planter in cold regions, chickpeas are sowing in small areas and in the traditional method (spraying the seeds and burying them with a moldboard plow). Increasing the yield by achieving a suitable planter can increase the area under mechanized pea cultivation in cold regions. To achieve a suitable planter, this project was carried out with the cooperation of the private sector in the Dryland Agricultural Research Institute in Maragheh for four years. The four planters, Barakat, Barakat Model BSK7, Aske Model 2200 and Sanayeh Keshtgostar Azarbayjan (SKA) were compared in four replications on a statistical basis of randomized complete blocks. The parameters of uniformity of planting depth, number of plants per unit length, height of the lowest pod and plant from the ground, number of pods per plant, grain and biomass yield and 100-seed weight were measured. The results of analysis of variance showed that except for plant height, the difference between treatments was significant in other measured parameters. The highest uniformity of planting depth and number of plants in the planting row was observed in SKA planter. But the highest grain yield with an average of 918 kg / ha due to having the largest pods per plant belonged to the Barakat planter. SKA, Aske and BSK7 planters were in the next ranks with 9, 26 and 30% decrease in grain yield compared to Barakat planter, respectively.

Pyrolysis is a thermochemical method for biomass conversion resulting from char, bio-oil and gas. Bio-oil can be used as a valuable renewable fuel or as a chemical in various industries. Char can also be used as a solid fuel, a cheap adsorbent, and raw materials for the production of bio-char derivatives and for agricultural applications. In the present study, the biomass pyrolysis of Euphorbia tirucalli was performed in a fixed bed reactor. Pyrolysis experiments for this study were to investigate the effect of temperature (450-530 °C) on the yield of pyrolysis products. Characteristics of pyrolysis products (bio-oil and bio-char) using instrumental chemistry methods such as field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA) and Gas chromatography–mass spectrometry (GC/MS) was investigated. The results showed that with increasing temperature, the yield of bio-oil and gas increases and the amount of bio-char decreases. The maximum yield of bio-oil (38%) was obtained at a temperature of 530 °C. Also, the maximum yield of various gases was about 39%. The highest thoracic effusion was observed at temperatures between 250-350 °C. The resulting acidic liquid is dark in color with a combination of chemical compounds including acids, alcohols, aldehydes, furfural, furan, phenols and some aromatic substances.

Using grain loss monitor system is one of the ways to measure the amount of the grain loss in the combine harvesters. The piezoelectric sensors that have a very great sensitivity are usually used in this kind of systems. Combine vibrations prevent proper and certain function of these sensors during the harvesting process. And it is necessary to prevent the transmission of these vibrations to grain loss monitor system in order to reduce the interference of the combine vibrations on the systems performance. Therefore, it is essential to use vibration absorbers before installing the measuring device on the combine harvester. In this study after designing of a vibration damping absorber, its differential equations were obtained. Then, the frequency response function of the system was obtained considering the external harmonic excitation and the effect of various parameters were examined. Finally, the performance of the designed vibration absorber was demonstrated with experimental tests. The results indicated that the designed vibration absorber had a high efficiency and resulted in 99% reduction of the acceleration transferred from combine to the sensor. The results of this study can be applied in designing and construction of vibration absorbers.

This project has been carried out in order to study the energy indicators in greenhouse cucumber production in Varamin region. For data collection, a greenhouse was selected for a concentrated survay and beside, 30 other cucumber production greenhouses were selected randomly and investigated in Varamin region. Energy inputs in this study included embodied energy in fertilizers, chemicals, machinery, labor, seeds, irrigation, and transportation. The results showed that the total energy consumption for greenhouse cucumber production in Varamin region was in average 4530.1 GJ/ha. The highest energy consumption was related to fuel (natural gas) and chemical toxins, which were respectively 4463.9 and 27.2 GJ/ha. The fuel energy consumption alone accounted for 98% of the total energy. The reason for high fuel consumption in these greenhouses was related to greenhouse warming, intensive because of inadequate greenhouse cover (plastic). The energy consumed directly in the production of greenhouse cucumber was 98.54 and the energy consumed indirectly was less than one percent. The average crop yield was 261 tons per hectare and its energy output equivalent was 208.8 GJ/ha. The energy ratio was calculated to be 0.046, net energy gain was (-4321) GJ/ha and the energy productivity was 0.057 kg/MJ. Finally, the results showed that optimizing gas consumption can significantly reduce the total energy consumption in cucumber production in Varamin region.