Research Article
Design and Construction
R. Meamar Dastjerdi; S. Minaei; M. H. Khoshtaghaza
Abstract
Non-destructive ultrasonic testing is one of the methods utilized to evaluate quality of agricultural produce. Transducers used in this method are made for basically industrial applications. Since ultrasonic attenuation of waves in agricultural produce is very high, industrial transducers cannot be used ...
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Non-destructive ultrasonic testing is one of the methods utilized to evaluate quality of agricultural produce. Transducers used in this method are made for basically industrial applications. Since ultrasonic attenuation of waves in agricultural produce is very high, industrial transducers cannot be used in agriculture and needs to be modified. This is done with horns that concentrate energy on a small area at a certain distance from the transducer. In this paper, an exponential horn was designed, fabricated and tested using theoretical and computer-aided methods. Results showed that highly sophisticated horns can be designed using computer-aided method with a high accuracy. Analysis of the number of elements on the natural frequency of horn proved that the analysis was not precise at the low number of elements. Therefore, the number of elements should be increased when natural frequency of horn is almost fixed. The minimum number of elements was obtained to be 300. A comparison between theoretical and computer-aided methods showed a desirable performance of the computer-aided method with an error less than 1% without solving very complicated equations. Based on statistical analysis of the data, the effect of produce thickness (potato and carrot) on the velocity of ultrasonic waves in the horned probe was not significant. However, for the un-horned probe, velocity changed significantly with the sample thickness which is not desirable. Therefore, horned probe is more suitable for non-destructive ultrasonic tests than the un-horned probe.
Research Article
S. I. Saedi; M. H. Aghkhani; A. Farzad
Abstract
Disk plows are one of the most important tillage tools. Two way (reversible) disk plows can perform continues plowing. So they can save time and costs and hence improve overall efficiency. In this study, a “two-way” disk plow was designed based on a λ-formed straight-line, four-bar ...
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Disk plows are one of the most important tillage tools. Two way (reversible) disk plows can perform continues plowing. So they can save time and costs and hence improve overall efficiency. In this study, a “two-way” disk plow was designed based on a λ-formed straight-line, four-bar linkage (Daniel mechanism). This design contains disk and rear wheel reversing mechanism, stabilization mechanism of the plow, a disk angle adjustment tool and transport condition for safe operation of the mechanism. Disk reversing mechanism was designed based on a geometrical analysis considering working condition of the disk plow. The suitable displacement of the plow’s frame was achieved by dimensional analysis of Daniel mechanism and a derived mathematical equation. The rear wheel mechanism was made by means of adding a slotted link to the previous four-bar linkage. The synthesized five-bar linkage was then analyzed for its kinematical and force conditions. For each analysis, related diagrams were plotted and discussed. This innovation has the advantages of low production cost and maintenance as well as easy operation, because of its design simplicity with minimum mechanical auxiliaries. The modeling and analysis was done by the aid of CATIA software.
Research Article
H. Ghorbanpour; M. H. Khoshtaghaza; M. R. Mostofi Sarkari
Abstract
Manual citrus harvesting is commonly performing hard, expensive and time consuming. In this study, a factorial experiment with a completely randomized design in three replications was performed to find out the effect of frequency (three levels of 5, 7.5 and 10 Hz), vibration time (three levels of 10, ...
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Manual citrus harvesting is commonly performing hard, expensive and time consuming. In this study, a factorial experiment with a completely randomized design in three replications was performed to find out the effect of frequency (three levels of 5, 7.5 and 10 Hz), vibration time (three levels of 10, 15 and 20 seconds) on harvesting capacity and losses of Thomson cultivar of orange. The results indicated that the effect of frequency and vibration time was significant (P≤0.01) on the harvesting capacity and losses, but their interaction effects weren’t significant. The harvesting capacity significantly increased by increasing frequency, and the highest harvesting capacity was 62.8 % at 10 Hz frequency. Although the harvesting capacity increased by increasing the vibration time, but there was no significant difference in vibration times between 15 and 20 seconds at 10 Hz frequency. Also the fruit loss was increased by increasing the vibration time. Due to these reasons, frequency of 10 Hz and vibration time of 15 seconds were selected as the most suitable condition for mechanized harvesting of this cultivar of orange. Finally a linear mathematical model was developed based on the frequency and vibration time for the harvesting capacity and fruit loss of Thomson cultivar of orange.
Research Article
M. Soleimani; M. Kasraei
Abstract
In recent decades, canola has been considered as the most important oilseed. Harvesting is the most major problem of canola cultivation, since canola pods are very sensitive to shocks and vibrations. Large amount of produce will fall on the ground especially when the combine's head is not adjusted properly. ...
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In recent decades, canola has been considered as the most important oilseed. Harvesting is the most major problem of canola cultivation, since canola pods are very sensitive to shocks and vibrations. Large amount of produce will fall on the ground especially when the combine's head is not adjusted properly. When canola harvested with a combine, the losses may reach up to 50%. The yields can be improved by decreasing seed losses during the harvesting operation. The objective of this study was to determine the optimal harvesting conditions of combine platform to minimize grain losses. In order to achieve this, a laboratory test stand platform was designed and built in the Department of Mechanics of Agricultural Machinery in Shiraz University. Three factors which are more effective on the losses were assessed to determine the best adjustments. These factors were combine forward speed at three levels; 1.5, 2 and 2.5 km h-1, cutter bar speed at three levels; 800, 1100 and 1400 cycles per minute and the relative linear speed of reel in respect of forward speed also at three levels; 1, 1.3 and 1.5. Desired experiment were accomplished on Talaeie variety at 16% m.c) d.b(. The grain losses were measured at each level, with three replicates. By considering the interaction of factors, results showed that the effect of these factors at 5% level was significant, and the minimum loss occurred at 2 km h-1 for forward speed, 1400 cut per minute for cutter bar speed and 1.5 for relative reel speed to forward speed.
Research Article
K. Gerami; M. Safari
Abstract
This experiment was conducted to study the effect of nozzle types and the time of herbicide incorporation in soil on weed control, using split plot design by randomized block design. The main plots were soil and herbicide mixing time and the subplots were nozzle types with three replications. This study ...
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This experiment was conducted to study the effect of nozzle types and the time of herbicide incorporation in soil on weed control, using split plot design by randomized block design. The main plots were soil and herbicide mixing time and the subplots were nozzle types with three replications. This study was performed in Karaj station of Seed and Plant Improvement Institute, located 25 km west of Tehran, in 2008. Treatments were including: T-Jet standard nozzle, Flood-Jet nozzle and Air induction nozzle as well as mixing with the soil immediately, three, six and nine hours after spraying. The parameters were measured includes: the number of weeds before spraying, 15 days and 30 days after spraying; dry weed at two stages of 15 and 30 days after the spraying; and yield of corn. The results revealed that the spraying quality coefficient was greater for T-jet nozzle compared to the other types. However Flood-jet nozzle had a wide range of corn weeds control in comparison to other treatments. Regardless of the nozzle type, the immediate incorporation of herbicide in soil after spraying significantly increased the yield. The time of herbicide incorporation in soil and poison intermixture with soil, from zero to 4.5 hours after spraying was superior to the other times. This was mainly due to different weeds reactions to the times of herbicide incorporation in soil after spraying, and also treatments effect on yield and weed dry weight. Combined data analysis showed that treatment combination of T-Jet nozzle (with time of herbicide incorporation in soil immediately and three hours after spraying), Flood-jet nozzle (with time of herbicide incorporation in soil immediately after spraying) and air induction nozzle (with time of herbicide incorporation in soil immediately, three and six hours after spraying) produced the highest yield than the other treatment combinations.
Research Article
E. Alishahi; M. Shamsi
Abstract
In this paper the separation of saffron stigma from stamen and petal in a vertical wind tunnel has been evaluated. A wind tunnel with adjustable speed of 0.1 m s-1 intervals has been developed and used for the experiments. Floating velocities of flower components (petal, stigma and stamen) were measured ...
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In this paper the separation of saffron stigma from stamen and petal in a vertical wind tunnel has been evaluated. A wind tunnel with adjustable speed of 0.1 m s-1 intervals has been developed and used for the experiments. Floating velocities of flower components (petal, stigma and stamen) were measured at one, eight, 38 and 60 hours after harvesting. Subsequently, the separation was tested by putting all flower components in the tunnel. The experimental results were also analyzed by fuzzy logic. The average floating velocities of stigma, stamen and petal at one hour after harvesting were measured as 3.21, 2.20 and 1.41 m s-1, respectively. The results showed that because of the high difference among the floating velocities of flower components, it is possible to separate the components in a vertical wind tunnel. Experimental results analysis showed that at the best condition which was one hour after harvesting and wind speed of 2.8 m s-1 in the tunnel, the system leaves 81% of the stigmas in the tunnel and blows out of the tunnel 84% of stamens and 89% of petals. The results also showed that as much as the time passes over the harvested flowers, the separation efficiency decreases.
Short Paper
H. Bagheri; A. Arabhosseini; M. H. Kianmehr
Abstract
In this research, solar drying of a thin layer of tomato slices was evaluated. The experiments were carried out at the air velocities of 0.5 and 1.0 m s-1 and thicknesses of 3, 5 and 7 mm. In order to find the most suitable form of thin layer drying model, nine different mathematical drying models were ...
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In this research, solar drying of a thin layer of tomato slices was evaluated. The experiments were carried out at the air velocities of 0.5 and 1.0 m s-1 and thicknesses of 3, 5 and 7 mm. In order to find the most suitable form of thin layer drying model, nine different mathematical drying models were fitted to the experimental data to determine the pertinent coefficients of each model. The goodness of the fit was determined by calculating and comparing the values of the correlation coefficient (R^2 ) Root mean square error (RMSE) and chi-square (χ^2) for all models. The Page model with R^2=0.9974 ,χ^2=0.01351 , RMSE=0.002 showed the best fit.
