JOURNAL OF AGRICULTURAL ENGINEERING RESEARCH
Year:2008 | Volume:9 | Issue:2|Papers Count:12

The single wheel tester is an experimental device used to measure wheel forces when studying the relation of soil and wheel in a soil bin or in the field. In the model under development, a special frame holding the test wheel is connected to a loading carriage by two pairs of vertical rails and four rollers to provide a floating connection. By applying a driving torque to the test wheel shaft, the tester frame and loading carriage moved along the soil bin and the net traction force developed by the test wheel is measured using a pair of force transducers (load cells). The driving unit consists of a 3-phase, 1.1 kW AC motor and a reduction gear unit (gear ratio 1:48). The drive unit is mounted on an independent frame which is mounted on the tester frame by a pivot shaft running through the center of mass of the drive assembly. A chain drive system transmits the output rotation of the drive unit to the test wheel axis. The torque transmitted to the test wheel was calculated by measuring the tension force of the chain using a load cell to measure the reaction force sensed by the pivotal frame during transmission. Rotary and linear encoders equipped with infrared sensors were used to measure angular and linear velocities of the test wheel and tester frame, respectively. The sensor output was sent to a data acquisition board to digitalize the data before being sent to a computer for further processing. The single wheel tester was capable of measuring net traction, linear and angular velocities, slippage and driving torque of test wheels as large as 25 em in width, 70 em in diameter and with a maximum net traction of 600 N and maximum torque of 170 N-m. During the evaluation tests, the traction parameters of an agricultural tire with an inflation pressure of 140 kPa, intended for a walking tractor, were measured. The evaluation results were recorded in diagrams of net traction force, driving torque, angular velocity; travel speed and wheel slip along a 2.5 m test track in a laboratory soil bin.

This study investigates the vertical replacement of salts, variability of electrical conductivity (EC) and soil acidity (pH) due to direct electrical current. A Plexiglas cylinder 100cm in depth with a 14 cm radius was used as a soil container and filled with uniform moist soil to 90 cm. During the experiments, the bottom 10 cm of soil in the cylinder was kept saturated. A steel bar was used as a positive electrode in the saturated part of the soil. Wire mesh was used as the negative electrode and was placed 10 cm in depth from the surface of the soil. A current of 80 V and 0.3 amp was applied between the saturated and upper part of the soil. It was found that, after one week, the Na+ concentration increased from anode to cathode (as for the control), while Ca++ and Mg++ decreased from anode to cathode. It can be concluded that Na+ moves from anode to cathode, but Ca++ and Mg++ move from cathode to anode. This replacement of ions is important in soil alkalinity reclamation. In this study, the mean decreased from 0.9 to 0.49. Also, the average electrical conductivity, or salinity, decreased in the soil column, moving from cathode to anode. These means were 4.1 and 1.1 ds/m for the control and treatment, respectively. Change in the acidity of the soil was not significant.

Riverbank erosion, land loss and associated sedimentation are river engineering and water resources management problems of global significance. The ability to predict riverbank stability on eroding rivers is the prerequisite of developing a channel width adjustment model and is essential for estimating riverbank erosion and associated sedimentation. In this research, a detailed model for stability analysis of riverbanks is introduced. Contrary to most available models developed based only on one type of planar or rotational failure, the new model includes both these types of failure, providing the ability to analysis bank stability using other available methods and compares the results. Furthermore, this new, unique model has the ability to analyze riverbank stability against cantilever failure. The most suitable analysis method was first selected based on bank material characteristics and stratification and the height and slope angle of the riverbank. The stability of the riverbank was then analyzed based on probable failure methods. The application of the new model providing examples of different types of failure is described.

In this study, the performance of different cultivation methods on sugar beet fields was evaluated. Eight treatments were considered: a) use of a rolling cultivator twice during the growing season; b) use of a rolling cultivator three times during the growing season; c) use of a crescent cultivator twice during the growing season; d) use of a crescent cultivator three times during the growing season; e) use of a furrower as a cultivator twice during the growing season; f) use of a furrower as a cultivator three times during the growing season; g) manual weed control twice during the growing season; and h) manual weed control three times during the growing season. A randomized complete block design with three replications was used in this research. Parameters such as sugar beet yield, percentage of sugar, sugar yield, percentage of sugar in molasses, weeds remaining in the field and nitrogen, potassium, and sodium content of the sugar beet root were measured for each treatment. Results show that there was no significant difference between the treatments for sugar beet yield, percentage of sugar, percentage of sugar in molasses, and nitrogen and potassium content of the sugar beet root. The difference between treatments was significant for weed weight remaining in the field, sugar yield, and nitrogen and sodium content of the sugar beet root. Of the treatments tested, manual weed control three times during the growing season showed the best performance for weed control and use of a furrower as a cultivator twice during the growing season produced the poorest performance. Use of a rolling cultivator three times was the most economic of the methods tested.

This study investigated the effects of land size and two leased and private fanning systems of machinery on economic efficiency and factors such as total production cost per hectare (ratio of total cost of agricultural inputs and operations to farm size), total income (ratio of product and byproduct value to farm size), yield (ratio of crop production to farm size) and degree of mechanization for irrigated canola fanning in Fereydoon-shahr in Isfahan province in Iran. The data was collected using questionnaires distributed to 239 participants. The statistical analysis was carried out using a factorial test. The results showed that the fanning system had no effect on economic efficiency and total cost but had a significant effect (at the 1% level) on total income. This was more marked in the private fanning system. The relationship between fanning system, yield and degree of mechanization was significant at the 5% level. In the private fanning system, the highest yield was obtained. Results also showed that land size appeared to have a significant impact on economic efficiency, total cost, total income, crop yield and degree of mechanization. As land size increased, these factors also increased, except for the degree of mechanization, which showed an inverse relationship.

Evaluating drainage systems, exploring their strengths and weaknesses, provides a comprehensive perspective to designers and organizers for optimum design and implementation of guidelines for the future. This study was conducted at an experimental site consisting of three plots on a subsurface drainage network under operation in Behshahr, a coastal region in northern Iran. To evaluate system performance, discharge rates from laterals and the depth of water table between laterals were monitored for a period of three months during the autumn. A second degree equation similar to the Hooghoudt formula was developed to show the relation between the hydraulic head and discharge rate. This equation was used to estimate the hydraulic conductivity (K) and equivalent depth (d) of the impermeable layer. The obtained K for the three plots ranged from 1.4 to 2.4 md-1, which was greater than the design value. This analysis also showed that the laterals were placed on the permeable layer. The Glover-Dumm equation was used to show the rate of water table fall and to calculate the specific yield (ys) and reaction factor (a). Based on these results, the actual a was 8%, which is greater than the design value of 4%, and the average y s obtained was 5.7%, compared to the design value of 7.7%. From these results, it can be concluded that the lateral spacing was overestimated.

The current study investigated and compared data generation methods for groundwater modeling. These methods can be divided into two classes; geostatistic and probabilistic. By comparing geostatistic methods, the best method was chosen and the hydraulic conductivity of the aquifer was generated for a study area in a grid (9-cell) format. After observing weak spatial correlation between the data, the probabilistic method was then considered. The Monte Carlo technique was used for data generation for the governing distribution function using the probabilistic method. Finally, the results of the two methods were compared. The ground water model used in this research was PMWIN 5.3 (MODFLOW). This model was used to predict the future state of an aquifer by using the generated data and time series of precipitation. Existing input data processing, data generation by geostatistic/stochastic methods and representation of model output were performed using ARC/INFO GRID.

Olive oil is one of the oldest known vegetable oils, ranking sixth in world production. Since it is extracted from fresh fruit and used without aging, the conditions of oil production are very important. During the extraction of virgin olive oil, the milling and malaxation steps are vital for increasing oil yield and quality. In this study, the effect of milling (single or double), temperature of malaxation (25, 35, 45, 60°C) and duration of malaxation (15, 30, 45, 60min) on yield and quality (acidity, peroxide index, color, carbonyl values) of virgin olive oils (cultivar Roghani) were investigated. The results showed that double milling increased oil yield, but that the type of milling had no significant effect on oil quality. Increasing temperature and duration of malaxation increased oil yield, however oil production increased substantially up to 35°C and 45 min but did not show a significant difference after that point. An examination of the qualitative characteristics of oil showed that, under the conditions tested, there was no significant difference in quality. The oil produced was of the highest quality. It was concluded that the optimal extraction method for the production of good quality oil with a satisfactory yield is to employ double milling with malaxation for 45 min at 35°C.

In this research, the total torque input and output shafts were subjected to are used to formulate two differential equations using applied dynamics and fluid mechanics. The equations show that the input and output torques are a function of the constant geometrical parameters of a torque converter, including internal and external diameters of vanes, angle and length of vanes, cross section area between vanes, density of fluid, and inertia of the torque converter turbine. The variables in these equations were cross flow between vanes and output shaft speed. The equations were solved using MATLAB software. Simulation in MATLAB uses two inputs and two outputs. Eighteen physical parameters from an actual torque converter were measured and substituted as fixed parameters in the equations and diagrams of the variable parameters (flow between vanes and output shaft speed) were obtained. This diagram showed an increase from the beginning for the coupling phase. The simulation showed that the torque converter performs better using dense fluid.

Soil infiltration characteristics affect the design, evaluation and management of furrow irrigation over a field. On the other hand, different variables influence furrow infiltration, making infiltration modeling for a field a complex process. This study was conducted to investigate the direct and indirect effects of all variables affecting furrow infiltration. The blocked furrow method was used to measure furrow infiltration for a field with soil of sandy loam. Results showed that infiltration time was the most effective variable affecting cumulative infiltration by directly and significantly affecting furrow infiltration. The relative contribution of the filtration time to the furrow infiltration was seven times more than the contribution of the wetted perimeter and 2.5 times that of the flow section area. An additive and nonlinear model was proposed to describe field-wide cumulative infiltration using the observed data. The proposed model described approximately 89% of the variation in field-wide cumulative infiltration.