نشریه مکانیزاسیون کشاورزی
سال هشتم شماره 1 (بهار 1402)

Scheduling projects in agriculture include operations and activities that are carried out in a certain order and within a certain period of time. If these operations and activities are not performed on time, due to the quantitative and qualitative decline of the product, a heavy decrease in the income of the farmer or agricultural unit will occur, and these costs are invisible. On the other hand, agricultural operations require the use of resources for implementation, which are usually limited, and if the activities are not optimally allocated, the possibility of the activities not being on time increases. In order to reduce the costs of not being on time, these projects require planning, scheduling and scientific and logical management of time and resources. This has become a standard problem in the field of project scheduling, which has attracted many researchers and they have used different scheduling methods, including exact methods and exploratory and meta-exploratory methods. As a result, various methods of project scheduling problem with limited primary resources have been developed. This article is an overview of research methods and analysis of existing methods that have been published so far. In this article, the goals and approaches to solving the project scheduling problem have been investigated, taking into account some existing works in the field of agriculture, as well as related data.

This study was conducted with the aim of determining the energy and indicators and environmental effects in the process of fish farming in Ilam province. The suitable climate and the existence of cold-water springs in the mountains of Ilam province have caused the prosperity of fish farming in this province. The required information was obtained through questionnaires and interviews and then the input and output energies and energy indicators energy and environmental indicators were calculated using the life cycle assessment method and using Simapro software. The results showed that the total input energy per one ton of coldwater fish (rainbow trout) was 44618.7MJ. Growth feed trout (GFT) with a share of 38.61 % had the highest energy consumer input in the production of rainbow trout. The amount of energy ratio, energy efficiency, energy intensity, and net energy gain indicators in cold-water fish production was 0.1784, 0.0214 kg/MJ, 44.61 MJ/kg, and -36658.7 MJ/ton, respectively. In coldwater fish farms, the share of direct, indirect, renewable, and nonrenewable energy was 42.16, 57.83, 77.15, and 22.84 %, respectively. After normalization of environmental indicators, it was found that in fish production, marine aquatic ecotoxicity index and then fossil resource depletion, acidification, global warming and eutrophication indices have the highest amount of environmental pollutants. The biggest environmental burdens in fish farms are from the process of producing fry, feed, electricity, oil fuel, copper sulfate.

Mass flow rate measurement has application in many industrials, e.g. silos, ports, food and drug industry. Mass flow sensors are used in cereal combines as well. Installed mass flow sensors on the combines creates some problems such as; cost, precision, recalibration and sensitivity for environmental conditions. So, introducing a new sensor based on new technology would had potential for future installation. A mass flow rate measurement sensor based on electrical capacitance tomography constructed and evaluated in this research. Defining the best discretization method for solving potential equations in FEM was the main objective of this research. Therefore, four discretizing method are compared and results are evaluated from run-time and precision viewpoint. According to results, the finer elements near the electrodes and increasing element numbers in such a way that don’t break the in-situ condition would be the best cases. The ECT system with fine elements and mesh numbers of 2048 would be applicable for mass flow rate measurement in combine harvesters.

Sesame harvesting is mainly done manually due to the use of dehiscence cultivars and high seed loss in mechanized harvesting. In recent years, with the introduction of non-dehiscence cultivars, the mechanized harvesting of sesame has become possible. In this study, the traditional and mechanized methods of sesame harvesting were investigated in terms of seed loss, cost, energy consumption and time required for harvesting. Data of traditional system were collected from farmers in Dezful, Shush and Andimeshk counties and data of mechanized system were obtained from Shahid Rajaei Agricultural production Company in Dezful. In the mechanized harvesting, the seed loss were measured in three amounts of seed planting rates (5, 10, and 12 kg/ha) and three ground speeds of the combine harvester (1.5, 2 and 2.5 km/h). The average seed loss in the combine was 4.83%, of which more than 94% was related to the combine header. The findings showed that with the increase in plant density, seed loss in combine is greatly reduced. The average labor in traditional harvesting was 315 labor-hours, which was 98 times more than in the mechanized method. The average cost of harvesting in traditional and mechanized methods was calculated as 49.4 and 2.7 million rials/hectare in 2019, respectively. The input energy in traditional and mechanized harvesting was 2088 and 1510 MJ/ha, respectively, that in the traditional method, human energy was the major part of the input energy. The results showed that the use of non-dehiscence cultivars and mechanized harvesting allows the development of sesame cultivation.

One of the most important stages of walnut processing is cracking the hard skin and shelling it. In this research, to reduce the mechanical damage and improve the extraction quality of walnut kernels during shelling, the fracture properties of the walnut shell were evaluated in a new uniaxial compressive loading test by creating a lateral deformation limitation called the enclosed. The fracture properties of walnut shell for the genotype of hard shell walnut were investigated due to the variables of loading mode, loading direction, and size of a walnut. The results showed that the effect of the state of walnut loading (free and enclosed) on the fracture force and fracture energy was significant at 1% and 5% probability levels, respectively. The breaking force of the hard shell walnut was 273.96 and 441.47 N for free and enclosed loading states, respectively. The breaking force along the longitudinal axis (392.56 N) was significantly more than in other loading directions, such as thickness or suture on the skin (347.85 N) and width (332.65 N). In general, observations showed that in the case of enclosed walnut loading, the rupture development on the shell surface was more than that of freeloading, which can be used as an idea for making a high-performance nutcracker machine.

This research presents a model for the analysis of sugarcane basket emptying operations. Traffic of sugarcane carrying baskets in front of the factory door will cause a long waiting line to form. Factors influencing the formation of queues include shift changes, accidents due to tractor crowding, tractor breakdowns, and factory shutdowns, which will lead to an increase in the time intervals between harvesting the crop and emptying the canes. Using queuing theory, the relevant system was simulated as a based model and the effect of each of the existing factors on the amount of time wastage and queue formation was evaluated. Based on the three scenarios (the investigation of queuing order, improve the bottleneck by deploying existing or non-existing discharge sources) proposed and the analysis of the system, based on the realization of each of the scenarios, the costs and queue conditions were investigated. According to the investigated cases, it was concluded that both sources in the factory should be used to empty the canes during the peak harvest time. The waiting time of the baskets in the system in the first, second and third scenario has decreased by 2%, 30%, and 59%, respectively, and the exit rate of the baskets has increased by 1.56%, 100%, and 198%, respectively. Comparing the efficiency of the scenarios using TOPSIS method according to the criteria of waiting time and cost showed that the second scenario has the highest rank.