مجله پژوهش های مکانیک ماشین های کشاورزی
سال سیزدهم شماره 4 (پیاپی 33، زمستان 1403)

The present research was conducted to evaluate the energy-economic and environmental indexes in two methods of rainfed fodder production (vetch pure cultivation and vetch-barley mixed cultivation) on a farmer's farm in Khorramabad county in the 2021-2022 cropping year. Planting vetch in a pure form with a density of 250 seeds/m2 and vetch-barley mixed cultivation with a ratio of vetch:3 and barley:1 was considered. According to the results, the average yield of wet and dry fodder in vetch pure cultivation was 8482 and 2800 kg/ha, respectively, and for vetch-barley mixed cultivation, it was 17950 and 6000 kg/ha. Comparison of the average yield using Student's t-test showed that the difference between wet and dry fodder yield mixed cultivation of vetch-barley with pure vetch cultivation was statistically significant. The total average of input and output energies in pure vetch cultivation and vetch-barley mixed cultivation (8675.25 and 48244 MJ/ha) and (8795.08 and 98880 MJ/ha) respectively, and the values of energy ratio and energy productivity in two methods of fodder production were calculated as (5.56 and 0.322 kg/MJ) and (11.12 and 0.682 kg/MJ), respectively. The global warming potential was obtained in the vetch pure cultivation and the vetch-barley mixed cultivation, respectively, 566.5 and 578.9 (kg eq. CO2)/ha. Also, the average net return and the benefit-cost ratio of rainfed fodder production in vetch pure cultivation and vetch-barley mixed cultivation were estimated as (40793000 Rial/ha and 1.51) and (173473000 Rial/ha and 3.05), respectively. According to the results of the evaluation of energy-economic and environmental indexes in two methods of rainfed fodder production, vetch-barley mixed cultivation is recommended as the superior treatment in the region.

Dryers play a very important role in the processing of food, chemical and pharmaceutical products. The drying performance depends on various factors such as the type of dryer, the temperature and speed of the incoming air to the dryer, the size and amount of incoming materials, and the time the materials stay in the chamber. For this reason, it is necessary to carry out specific studies in the field of drying products. On the other hand, designing, manufacturing, and equipping dryers with sensors to measure various characteristics is a costly process, and in recent research, numerical and simulation methods have been used to analyze dryers. Therefore, in this article, the characteristics affecting the drying process in a cross-flow fluidized bed dryer with a tray were investigated by CFD method. For this purpose, the mass flow rate effect of materials in 3 levels is 2.76, 5.76 and 8.1 kg/h, the velocity of incoming hot air in 4 levels is 2.5, 3, 4 and 5 m/s and hot air temperatures in 4 levels of 50, 60, 70 and 80 degrees Celsius on the speed and pressure inside the chamber was checked by ANSYS fluent 18 software. The results showed that increasing the temperature caused an increase in the air pressure and speed inside the chamber and in the bed. Increasing the feed flow decreased the pressure and velocity.

The interaction of wheel and soil has received much attention from the researchers of this sector due to its effects on energy consumption and soil characteristics, especially in the field of agriculture. In this research, the amount of wheel indentation in the soil and the rolling resistance of the moving wheel, which are the determining parameters in the wheel-soil interaction, were measured using a wheel tester in the laboratory soil bin. Tests in 2 different levels of speed (0.386 and 0.879 km/h), 3 different levels of tire pressure (18, 25, and 32 lb/in2) and 3 different levels of vertical load on wheel (150, 300, and 450 kg) were carried out in the form of a randomized complete block design (RCBD) in 3 repetitions and a total of 54 treatments. Then, using adaptive neuro-fuzzy inference system and multivariable regression model, the amount of indentation and rolling resistance were predicted. In order to evaluate these models, correlation coefficient and mean square error were used. The results showed that inflation pressure, vertical load, and forward speed of the moving wheel have significant effects on the wheel indentation in the soil (P<0.01). They do not have correlation coefficient in predicting the amount of indentation and rolling resistance by adaptive neuro-fuzzy inference system models was equal to 0.99 and 0.69, respectively, which was much higher than the correlation coefficient in regression models (0.87 and 0.40, respectively). Also, the mean square error in adaptive neuro-fuzzy inference system models regarding the indentation and rolling resistance of the wheel was 0.0231 mm2 and 0.0101 kgf2, respectively, which is much lower than the mean square error in the regression models (0.864 mm2 and 0.918 kgf2, respectively). Therefore, adaptive neuro-fuzzy inference system models have higher accuracy and less error than regression models.

This study investigates the application of the random forest algorithm in spectroscopic methods, especially Vis-NIR (Vis-NIR) spectroscopy, to predict key quality characteristics of cherries. This paper aims to present a reliable and efficient method for the non-destructive evaluation of sugar content, acidity, and firmness, which are essential factors determining cherry quality and consumer acceptance. In this study, 400 random samples of cherry products were prepared. Spectral data were obtained. Next, the spectral data obtained from Vis-NIR spectroscopy were evaluated by the Relief method, and five effective wavelengths (for firmness, soluble solid content and cherry acidity, wavelengths between 615 to 650, 650 to 675 and 818 to 945, respectively) were selected separately for each of the values of the dependent variables (sugar, acidity, and hardness values). Next, the reflection intensity values related to the selected effective wavelengths were selected as input features for the random forest model. The performance of the model was evaluated in terms of prediction accuracy through cross-validation and independent evaluation tests, using root mean square error (RMSE) and correlation coefficient (CC). The results show the effectiveness of the random forest algorithm in accurately predicting sugar content (with a correlation coefficient of about 0.93 and a mean square error of about 3.4), acidity (with a correlation coefficient of about 0.95 and a mean square error of about 0.87) and cherry firmness. (With a correlation coefficient of about 0.92 and a mean square error of about 1.2) is based on spectral information. This approach provides a quick, non-destructive, cost-effective solution for product quality assessment in the cherry industry. Also, with progress in this area, producers and stakeholders can make informed decisions about harvesting, sorting and post-harvest processes.

The correct method of spraying herbicides is an important factor affecting weed control. In this regard, three types of herbicide sprayers including tractor mounted boom sprayer, knapsack atomizer and knapsack boom micronair were investigated to control weeds in the corn fields of Safiabad Agricultural Research Center, in Dezful, Iran. In order to compare the performance of these three sprayers, a randomized complete block design with five treatments and three replications was implemented. The treatments of this experiment included spraying by a mounted tractor boom sprayer, knapsack atomizer, knapsack boom micronair, and weeding by a human, as well as no weeding and spraying. After identifying the types of weeds in the field, nicosulfuron herbicide was applied. The results showed that the lowest means of weeds dry weight including Cleome viscosa, Corchorus olitorius, Cyperus rotundus, Physalis alkekengi and Convolvulus arvensis belonged to the micronair sprayer treatment with the values of 2.53, 2.92, 2.94, 1.43 and 1.92 g.m-2 respectively. The study of corn yield and yield components showed that among the spraying treatments, the highest mean of biological yield, number of corn plants per unit area, corn ear weight per unit area, number of seeds in a row of an ear, wood weight of an ear, thousand-seed weight, corn plant height, a corn ear weight and seed weight of an ear of corn belonged to micronair sprayer treatment with the values of 30 t.ha-1, 74000 plants per hectare, 12.93 t.ha-1, 36.3 seeds per row, 46 g, 415 g, 299 cm, 260 g and 216 g respectively.

In developing countries, transplanting in a traditional way is one of the conventional methods at the farm level. In this method, due to the environmental pollution left over from plastic trays, it destroys the structure and soil texture. For this reason, nowadays, they use an alternative method, degradable pots. In this research, the characteristics of two types of renewable pots were investigated using a pressure test device with three humidity levels in three repetitions. The general goal is to introduce the best pot for planting seedlings in a smart device to develop technical knowledge and increase the productivity of planting with the least waste in Iranian farms. Is. The results showed that the type of pot, for parameters density, ultimate stress, displacement in ultimate stress, yield stress and displacement in yield stress at the level of 5% and water absorption time, for parameters density, humidity, ultimate stress, displacement in ultimate stress , yield stress, displacement in yield stress and pot thickness is significant at 1% level. Also, the result of the simulation test of incomplete conical cylinder and square pyramid renewable pot using Ansys software with laboratory data showed a correlation coefficient of 88 and 91%, respectively. According to the present research, the best option to use in the smart planter for planting is the sample of the incomplete conical cylinder pot in the initial moisture content and the duration of 30 minutes of water absorption.

Urban air pollution is primarily attributed to the use of gas oline-fueled cars with internal combustion engines, leading to a depletion of fossil fuel reserves, increased pollution from combustion, and respiratory illnesses. One approach to mitigate combustion - related pollutants is the incorporation of biofuel - based additives. Glycerin , a byproduct of biodiesel production, plays a crucial role in the synthesis of these additives . This study focuses on converting glycerin derived from sunflower oil into Solketal – acetin , a novel biofuel blend with gasoline. This unique fuel blend exhibited favorable characteristics at specific composition ratios . The performance of the Solketal - acetin additive blend with gas oline was evaluated in a 150 cc motorcycle under various loads (1.2 Nm, 6.2 Nm, 11.2 Nm) and speeds (570 rpm , 850 rpm , 1044 rpm, 1269 rpm, 1427 rpm) to assess fuel exergy efficiency and net work exergy input. At a pressure of 11.2 Nm and a speed of 1427 rpm -1269 rpm, engine shutdown occurred across all fuel injections due to excessive pressure and inadequate thermal capacity of the fuel. The findings indicated that the addition of triple compounds to gasoline fuel enhanced the braking power exergy due to the high density of these compounds.

Today, the consumption of fossil fuels is known to be unsustainable due to the rapid destruction of valuable resources and the production of environmental pollutants, and it has prompted researchers to find a good alternative to this by using renewable energies and expanding them with the help of appropriate processes. Biodiesel is one of the best-suggested sources. Oscillatory baffled reactors with high stirring intensity in less time and more volume has attracted the attention of many researchers in recent years. This study aims to evaluate the two-chamber oscillatory baffled reactor in the continuous production of biodiesel. The ultrasonic system has been used as a suitable pre-mixer, and waste oil has been used to reduce production costs. The molar ratio of methanol to oil (1:6, 1:9, and 1:12), time (1, 3, and 5 minutes), oscillation frequency (2.4, 3.7, and 4.9 Hz), and temperature (40, 50 and 60 °C) are the four factors that were investigated in this research. The physical and chemical characteristics of the biodiesel produced follow ASTM standard D6751. The response surface method was used to optimize the content of methyl ester produced, and The results indicated that the highest performance of biodiesel is 95.28%, along with the lowest energy consumption of 58.80 in the molar ratio of 8.01, time of 2.55 minutes, oscillation frequency of 3.64 Hz and temperature 49.05 degrees Celsius. The production of biodiesel with a high conversion percentage and in a larger volume by the fluctuating flow reactor, which was associated with a shorter reaction time, was another result of this research.