Agricultural systems engineering (greenhouse, fish farming, mushroom production)
P. Shamsi Roodbarsar; S. R. Mousavi Seyedi; D. Kalantari; K. Ghasemi
Abstract
IntroductionIt is predicted that the world population will grow to 9.3 billion by 2050 and the urban population will increase by 73%, growing from 3.6 billion to 6.3 billion. This huge population requires abundant food production. A plant factory with artificial light (PFAL) is a closed growing system ...
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IntroductionIt is predicted that the world population will grow to 9.3 billion by 2050 and the urban population will increase by 73%, growing from 3.6 billion to 6.3 billion. This huge population requires abundant food production. A plant factory with artificial light (PFAL) is a closed growing system that is insulated against heat and air. The plants grow on shelves under horizontal artificial lighting. The main goal of PFAL is commercial plant production, but mini PFALs do not have commercial goals and are used to produce plants in small domestic sizes. Plants that are less than 30 cm tall, and grow well in relatively low light conditions and at high planting densities, are suitable for the plant factory. Therefore, plants such as rice, wheat, and potatoes are not suitable for cultivation in a plant factory.The main purpose of this research is to study the proper light quality for growing radish plants. All light treatments had a significant effect on biomass, sugar, and photosynthetic pigments of radish. The results showed that the highest amount of chlorophyll a was 0.964 mg g-1 fresh leaf weight and the lowest amount was 0.318 mg g-1 fresh leaf weight. For chlorophyll b, the highest value was 0.666 mg g-1 wet weight and the lowest value was 0.229 mg g-1 wet weight. The highest and lowest carotenoid contents were 74.75 mg g-1 and 30.6 mg g-1 wet weight, respectively. The highest sugar content was 0.717 μg g-1 dry weight and the lowest was 0.02 μg g-1 dry weight. The highest fresh and dry weights of the plant were 0.27 g and 0.014 g, respectively, while the lowest values recorded were 0.155 g and 0.007 g, respectively. In this study, plant length was also examined, but no significant difference was observed between different light treatments. Based on these findings, it can be concluded that the light composition (R2, G0, B1) was the most suitable light regime for use in the designed system.Materials and MethodsThe plant studied in this investigation was radish. The place of growth was a vertically built system consisting of four floors, each divided into two sections. A controller was required in each section to regulate parameters such as light time, temperature, and moisture. The controllers were designed using Fritzing software and built with parts and sensors like DHT 11, Arduino UNO based on ATMEGA328P, Relay module Arduino, data logging shield, and driver module RC. A programming platform like Arduino was used to write codes for controlling the remaining parameters. This study tested seven different light treatments, plus sunlight as a control, to investigate their effects on radish growth. The light treatments were developed by adjusting the number of three different lights: red, green, and blue. LEDs were installed after designing and constructing the m-PFAL system. Based on previous research conducted in this field, all LED lights were positioned above the shelves to ensure that the plants received an appropriate amount of light in a vertical orientation. Additionally, light reflectors were installed beside the plants to provide proper lighting for the lower leaves. The experimental design involved a completely randomized design with eight treatments and three replications, and all data analysis was conducted through SAS software. The average comparison was performed using the Duncan method at a probability of 1% and 5%.Results and DiscussionThe results indicate that the light regime (R2, G0, B1) resulted in the highest amount of chlorophyll "a", which was significantly different from both the control and other treatments. The treatment with the lowest amount of chlorophyll "a" was (R1, G0, B0), which did not differ significantly from the control or (R1, G1, B1). The treatment with the highest amount of chlorophyll "b" was (R2, G0, B1), which differed significantly from the control but not from (R2, G1, B0) or (R1, G0, B2). Using a mixed light treatment of blue and red resulted in higher amounts of photosynthesis pigments, especially when the red light was more prevalent. The treatment with the highest wet weight was (R2, G0, B1), which did not differ significantly from natural light. The treatment with the lowest wet weight was the just red light treatment, which was much lower than the other treatments. The dry weight of the radish was 4-6 percent of its wet weight, and the treatment with the highest dry weight was (R2, G0, B1), which did not differ significantly from (R0, G1, B2) or (R1, G0, B0). The treatment with the highest amount of sugar was (R2, G0, B1), which was significantly higher than other optical regimes used and natural light. Because the production of carbohydrates and sugar is directly related to photosynthesis, it can be concluded that the state of photosynthesis was most proper in the (R2, G0, B1) treatment.ConclusionThis study investigated the optimal light quality for the healthy and rapid growth of radish plants in a plant factory. LED lights can be an excellent alternative to natural light when there are limitations, such as in greenhouses or multi-floor plantings. The results show that the best light mixture was red and blue lights, with more red light than blue light, while the worst light regime was just red color, which had a negative effect on all parameters.
Design and Construction
O. Esmand; S. R. Mousavi Seyedi; D. Kalantari
Abstract
Introduction The use of new technology in planters is one of the most important factors in the advancement of agricultural science. In the present study, an electronic warning system has been designed and implemented to prevent large seeds from falling from the fall pipe into the ground groove. In this ...
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Introduction The use of new technology in planters is one of the most important factors in the advancement of agricultural science. In the present study, an electronic warning system has been designed and implemented to prevent large seeds from falling from the fall pipe into the ground groove. In this study, three types of corn, bean and soybean seeds have been used, using two laser and microwave sensors. Viewing and comparison of the two sensors and their performance in two conditions of medium and high sensitivity in both laboratory and field conditions were conducted. In this case, the differences between the two sensors in different sensitivities have been evaluated and compared. The performance of the sensors in seed count has also been studied and compared. According to the results obtained in both cases, the sensors performance was acceptable, and especially in the maximum sensitivity of the sensors, they were able to handle well the clogs created in different situations (clogging down or above the fall pipe or emptying the seed tank). Detect and alert in a timely manner. Also, the count of seeds in all three seed types was recorded with high accuracy compared to the actual number. Materials and Methods Three types of coarse seeds (corn, beans and soybeans) as well as two types of sensors (laser and microwave) with two levels of medium sensitivity and high sensitivity were used for the experiments. Laser sensors are one of the most precise instrumentation and industrial automation tools that use laser light to detect objects or even precise distances. The function of the microwave sensor is that the high frequency waves are transmitted when the power supply is connected. These waves are reflected back to the module receiver if they hit objects. The open waves in the module are multiplied by the frequency of transmission by the mixer and a low-output (IF) signal is generated. The output frequency is equal to the difference between the frequency of the transmitted and reflected waves caused by the Doppler effect. Based on this frequency, the presence of a moving object and its speed are detected. Experiments were carried out at both laboratory and field levels and in both moderate and high sensitivity modes using variable resistance mounted on the controller. The equivalent distance for each seed test is 100 meters, so twice for each seed in the laboratory and field level for each of the laser and microwave sensors in both high and medium sensitivity modes. In this system, in case of falling pipe clogging due to seed accumulation or mud under the falling pipe or other factors, an alert system (warning beep), along with the corresponding LED light, indicates a problem in the seed fall system and the operator alerts paying attention to the LED light (green or red) will detect the problem. Results and Discussion The results indicated that by installing a variable resistance inside the circuit, different sensors can be created in the sensors. Increasing the sensitivity of the sensor as much as possible can cause higher the efficiency of the sensor. In the two cases of medium and high resistance, sensors work with medium and high sensitivity. It works since both modes have been tested and the results have been satisfactory. The accuracy of counting and seed detection accuracy between two laser sensors and microwave sensors in two medium and high sensitivity modes were calculated and evaluated. The experiments in the laboratory showed that the difference in the number of seed count by laser sensor compared to the actual number in maize seed at medium and high sensitivity were 87.4% and 94.3%, respectively, in bean seeds 89.1% and 94.2%, respectively. And in soybean seed were 89.4% and 92.3%, respectively. Conclusion The developed embedded system can successfully check and announce the instantaneous state of three types of grain tested (corn, beans and soybeans) in the seed delivery tube of a hand single-row planter with visual cues (on or off LED lights) and audible signals (on or off the alarm), whenever there is a grain flow or no grain flow. Likewise, the developed system can show the blockage at the end of the seed delivery tube with visual indications of the green and red lights on or off and the alarm sound described in detail. These warnings are indications of a fall pipe failure or lack of grain flow in the grain measuring mechanism toward the opening groove and then into the ground. This type of detection alerts the operator in a timely manner by monitoring the status of the grains in the measuring system and ensuring that the grains are located in the ground.
Sh. Sedighi; D. Kalantari; J. Rédl
Abstract
IntroductionThe most important adverse effects of noise on humans have reduced work efficiency and physiological damaging effects such as increased heart rate, high blood pressure, permanent and temporary hearing loss, impaired vision, disrupting the body's balance system, causing nervous disorders and ...
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IntroductionThe most important adverse effects of noise on humans have reduced work efficiency and physiological damaging effects such as increased heart rate, high blood pressure, permanent and temporary hearing loss, impaired vision, disrupting the body's balance system, causing nervous disorders and even nervous disorders. Much of the occupational disturbance is due to acoustic vibrations in agricultural mechanization, which is affecting a large number of farmers. In this regard, most of the noise and vibration come from two-stroke or four-stroke engines that are used in lawn mowers, sprayers, pits and more. These high-vibration equipment causes a great deal of damage to their operators. Portable lawn mowers are popular for working in urban and rural areas due to their low cost, low maintenance cost, high maneuverability and affordability. Therefore, the possibility of optimizing the muffler of a small combustion engine for a lawn mower was investigated and studied in the present stud.Materials and MethodsTo optimize the existing muffler, geometry of the factory muffler was first redesigned in solidworks 2014 software. Then the optimized muffler, along with the factory muffler exported into ANSYS CFX software and simulated in terms of velocity and pressure distributions. To evaluate the built muffler and compare its performance with the factory standard muffler, the mufflers were then mounted on a DOMA’s lawnmower model WPGD501 with a 42 cm3 engine volume and tested outdoors in a radius of 5 m. All sound recording tests were performed in steady state at a distance of 1m with a 45° angle and position along the exhaust outlet to reconstruct the user's ear position. A digital thermometer TEM-8820 and a PSA-V01 digital barometer were used to measure the sound pressure and an environment temperature.Results and DiscussionThe results showed that at 3000 rpm, the sound pressure level of the modified muffler decreased by 6.4% compared to the modified muffler. The same decrease in sound pressure level was achieved at 5000 rpm, equal to 4.5%. The results of this study showed that with increasing engine speed, pressure changes in the muffler had an upward trend. These changes in the modified muffler increased by 0.02 kPa at 3000 rpm and by 0.07 kPa at 5000 rpm. According to the outputs of the FFT diagrams, the intensity and amplitude of the output frequencies from the modified muffler significantly decreased almost at most frequencies. Therefore, effective pressure difference (ΔPrms) was used for the further investigations. The results of this study showed that the pressure changes in the muffler had an upward trend with increasing the engine speed. These changes in the modified muffler increased by 0.02 kPa at 3000 rpm and by 0.07 kPa at 5000 rpm.ConclusionAccording to the results of the present study, by optimizing the internal muffler geometry of the lawn-mowers by installing internal blades and neutralizing the sound intensity inside the muffler, it is possible to reduce the sound pressure level by 4% to about 7% over the original muffler. It is a very simple and inexpensive method for the manufacturers of such engines.
Design and Construction
H. Dehghan-Hesar; D. Kalantari
Abstract
Introduction Optimizing the energy consumption in mechanized agriculture is becoming more important due to the limited energy sources in the world. In this regard, optimization of the cutting blades is presented in this study by modifying the geometric form of the blade to reduce the forage cutting energy. ...
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Introduction Optimizing the energy consumption in mechanized agriculture is becoming more important due to the limited energy sources in the world. In this regard, optimization of the cutting blades is presented in this study by modifying the geometric form of the blade to reduce the forage cutting energy. Hence, two new blades, inspired by the geometric profiles of front claws of mole crickets and teeth of grasshoppers were designed and built using the biomimetic method (the method for transferring biological solutions to the engineering ones). Finally, the new biomimetic blades were tested and compared with two other conventional blades (flat and bent blades) by cutting 8 different types of crops and weeds. Materials and Methods The main idea of building one of the blades was inspired by the geometric forms of mole crickets' scissors-like front legs and lower teeth of grasshoppers. Therefore, five adult mole crickets and five grasshoppers were collected from a farm in Kalat-e Naderi, Khorasan Razavi Province. In the next step, different images were captured from the front leg of mole cricket and tooth of grasshopper using the stereomicroscope (Nikon, SMZ-U, Japan). In the next step, the images were transferred to the image analysis software (Image J) and the boundary lines of images were selected. Then, the selected boundary lines were imported to SolidWorks software and the points on the selected curve were extracted. The obtained points were drawn in Matlab software and several fitting curves for the points were examined, e.g., Fourier function, Gaussian function, and polynomial function. According to the obtained results, the Gaussian profile was selected to design the blade with the highest correlation coefficient (R2=0.99), see Fig. 1d. To design the desired blade, a section of the Gaussian curve between points A and B were used. Finally, the biomimetic blade of the mole cricket and grasshopper were drawn in SolidWorks software (Fig. 1e). After designing the blades in the SolidWorks software, the biomimetic blades were built by a CNC machine. Results and Discussion In all the treatments, a significant difference was observed between the biomimetic blades and the conventional flat and bent blades according to the results of Tukey's test at the level of 5%. The obtained results showed that there was no significant difference between the mole cricket and grasshopper blades at the level of 5% for cutting. According to the results obtained in this study, there was a significant difference at the level of 5% between the grasshopper and flat blades for cutting alfalfa, clover, amaranth, orach, and poaceae; as well as between the grasshopper and bent blades for cutting alfalfa, clover, nutsedge, and amaranth, also between mole cricket and flat blades for cutting alfalfa, clover, purslane, amaranth, orach, paddy, and poaceae and finally between mole cricket and flat blades in cutting alfalfa, clover, nutsedge, amaranthus, and paddy. In this regard, no significant difference at the level of 5% was observed between the flat and bent blades for all cutting treatment. The batches containing 6 stems were used for cutting the soft stems with low shear stress and the batches containing 4 stems were used for cutting thick stems with high shear stress. Conclusion The results obtained in this study indicated that the geometrical form of the blade has a significant influence on the amount of required shear energy. The mole cricket biomimetic blade reduced the cutting energy compared to the flat blade by 23.37% to 52.51% (with the mean of 39.11%) and compared to the bent blade by 10.46% to 52.46% (with the mean of 32.8%). The grasshopper biomimetic blade also reduced the cutting energy compared to the flat blade by 15.78% to 53.82% (with the mean of 33.59%) and compared to the bent blade by 2% to 46.29% (with the mean of 27.87%). According to the results of this study, the mole cricket biomimetic blade showed better performance in comparison with the grasshopper biomimetic blade for cutting the plants and as a final result could be recommended to build the plant cutting blades.
Design and Construction
S. Hasantabar; S. R. Mousavi Seyedi; D. Kalantari
Abstract
Introduction Nowadays, due to growth and development of the husbandry and its worthiness in providing human basic needs, affecting parameters such as costs, efficiency and fuel consumption is significantly important. So, increasing the efficiency of threshing machine could lead us to huge savings in ...
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Introduction Nowadays, due to growth and development of the husbandry and its worthiness in providing human basic needs, affecting parameters such as costs, efficiency and fuel consumption is significantly important. So, increasing the efficiency of threshing machine could lead us to huge savings in energy. However using the conventional drums and concaves have some problems such as damaging seeds due to impact, complicated manufacturing technology and spending a lot of energy in separating process. Therefore in order to overcome above mentioned problems especially energy consumption, a new seed pod husker based on rubbing was designed, fabricated and tested in this research. Materials and Methods Practical tests of this device were carried out on soybean which was harvested in a farm of Babolsar city. The experimental design was simple randomized complete design with three replications. The rotational speed of rollers and distance between rollers varied in three levels of 110, 170, and 210 rpm and 7, 8, and 9 mm for soybean. The measured parameters consisted of efficiency, separation and loss. For designing the seed pod husker, the required electric motor power and the torque for separating seeds from its pods were calculated. After reviewing the physical and mechanical characteristic of some seed pod crops specially, soybean, a seed pod husker was designed in SOLIDWORKS 2013 software. In order to facilitate seeds separation from the pod, it was preferred to use the right-round and left-round Archimedes screw on the rollers. According to the preliminary evaluations, it was considered to use a speed range of 110 to 210 rpm; it was because of that the speed lower than 110 rpm was not able to open pods and the speed higher than 210 rpm caused hyper movements of pods. Analysis of variance (ANOVA) and mean comparisons and interaction between the parameters were performed using the SPSS 22 software. Results and Discussion The results indicated that the rollers were acceptable and sticking of pods were not seen. Results indicated that the efficiency of this device was increased with increasing the rotational speed and then was decreased. Increasing the rotational speed was led to increase separation. It is because of this fact that the performance of the husker’s component will be more powerful and crops suffer bigger impacts. The chart of device loss had a relatively upward slope. It could be due to a tougher collision between the seeds and the rollers. Increasing the roller distance, first decreased the efficiency of soybean and then increased that. The results indicated that separation efficiency decreased by increasing the distance. The reason for that was due to unavailable necessary force to separate the seed and pod. As the roller distance increased, the total losses of the device also increased. The reason for this was likely increasing in the movement of the seeds. Conclusion The results of practical tests and qualitative observations showed that the device had sufficient resistance against the maximum torque produced by the crop. Influence of rotational speed of rollers and rollers clearance on the efficiency, separation and loss were significant for new fabricated seed pod husker (p < 0.01). The capacity of the machine for soybean was 28.506 (kg hr-1). To achieve maximum efficiency, maximum separation and minimum loss for soybean, authors suggest using (9mm-170rpm), (7mm-210rpm) and (9mm-110rpm) compounds, respectively. Eventually, it is suggested to evaluate this machine for other seed pod crops and for other parameters such as germination percentage, electric conductivity and ergonomic issues such as noise and machine vibration. Of course, it is recommended to survey the impact of length of husking roller, shaft rotation method and thread types on measurement parameters.
Design and Construction
S. Mollapour; D. Kalantari; M. Rajabi Vandechali
Abstract
Introduction Nowadays, the best method for fertilizing trees is spot treatment via hole-digger. Conventional mechanical hole-diggers have several drawbacks such as auger’s non-continuous and limited speeds due to using a mechanical gearbox, and risks of getting stuck inside the hole and motor reaction ...
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Introduction Nowadays, the best method for fertilizing trees is spot treatment via hole-digger. Conventional mechanical hole-diggers have several drawbacks such as auger’s non-continuous and limited speeds due to using a mechanical gearbox, and risks of getting stuck inside the hole and motor reaction force to the operator. On the other hand, a three-point hitch hole-digger has problems such as the lack of maneuverability in confined spaces and high prices. Meanwhile, preparation of these hole-diggers by most farmers and gardeners has no economic justification. Thus, in this research it has been aimed to handle the mentioned problems and to optimize the working quality of hole-diggers via designing and manufacturing a new hydraulic hole-digger. Materials and Methods To start design the machine, displacement volume and power requirement of the hydro-motor and consequently displacement volume requirement of a hydro-pump were calculated using the appropriate formulas (70.83 cm3, 2.3 kW & 7.5 cm3, respectively). According to available hydro-motors and hydro-pumps in the market and using obtained values of displacement volume, an orbital hydro-motor, BMR-80 model with the maximum torque of 220 N.m and an external gear pump REXPORT-2APF8 with displacement volume of 8 cm3 and flow rate of 12 L.min-1 were chosen. In the following, hydro-pump’s parameters were used to select the internal combustion engine. The engine power requirement was 2.875 kW (3.85 hp); thus according to the available engines in the market, a single cylinder gasoline engine, WX168F-1 model that made in Kato company of China with 6.5 hp power and maximum speed of 3600 rpm was chosen. To transmit the power from the engine to the hydro-pump, a coupling DK-42 model was used. Also, two pressure gauges, LB-250 model with maximum pressure of 250 bars were used in the entrance and the exit of the hydro-motor. An hydraulic oil tank with total volume of 24 liters was made from a sheet metal with thickness of 3 mm. The helical auger used in this research, was made in china by LIONS Company with cone tip, total diameter of 200 mm and pitch of 180 mm. The fabricated digger has a working depth and diameter of 30 cm & 20 cm, respectively; rotational speed between 100-160 rpm and maximum power equal to 6.5 hp. In order to evaluate the stress distribution in the auger set, the static analysis based on maximum dynamic torque exerting on auger’s axle and maximum dynamic force exerting on auger’s blades, was used in SOLIDWORKS 2013 software. The maximum force 214.07 kgf (2100 N) proportional to the maximum exerting torque (210 N.m) from soil to the edge of the auger’s blade were considered in the modelling. Farm experiments were carried out in two citrus gardens with silty-clay and sandy-loam texture based on factorial test in Completely Randomized Design with three replications. Soil moisture content as high and low humidity levels (24.85% and 16.12% in sandy-loam and 25.95% and 16.48% in silty-clay) as the first factor and soil depth as the second factor varied in three levels of low, medium, and high (10, 20 and 30 cm), respectively. The measured parameters consisted of specific fuel consumption, machine efficiency, auger torque, auger power and used energy. To determine the auger’s torque, the oil pressure measurement method with two manometers was used in the entrance and the exit of the hydro-motor. After measuring the time and power needed to dig pits, for determining the used energy, the area under the power-time graph was calculated in Excel software. Also, to determine the fuel consumption during the experiments, the filled fuel tank method was used. Data analysis including analysis of variance (Anova), mean comparisons and interaction between the parameters were performed using the SPSS 22 software. Results and Discussion The numerical stress analysis results of the auger showed that the maximum von - Mises stress is occurred in the position of the blade-auger axis connections, with a magnitude of 86 MPa. The obtained experimental results in this study indicated that influence of soil depth and moisture content on the measured parameters were significant. in both soil textures and the influence of soil moisture on machine efficiency was non-significant in the silty-clay texture. With increasing soil depth, measured parameters excluding machine efficiency were increased in both soil textures. In high depth and also in low moisture, regarding to the increasing soil bulk density and shear strength, more torque was needed for the rotating auger in the soil that this has led to an increasing in specific fuel consumption of the device. Regarding the results obtained in this study, minimum specific fuel consumption value of the device (0.0014 liter pit-1) was obtained at the low working depth (10 cm) and the high soil moisture (25.95%) in the silty-clay soil. The hole-digger working capacity at 30 cm working depth and soil moisture content as high and low humidity levels in silty- clay obtained equal to90 and 88 pits per hour and in sandy-loam obtained equal to 101 and 95 pits per hour, respectively. Also, the maximum device’s power (2.548 kW) occurred in deep soil (30 cm) and low soil moisture in silty-clay texture. Conclusion Stress analysis and field qualitative observations results indicated that the fabricated device has sufficient resistance and strength against maximum torque from tested soils. Field evaluation of the fabricated machine showed that pit digging operations in soil is not appropriate in low moisture content because of the high fuel consumption and environmental pollution issues.
H. Gholami; D. Kalantari; M. Rajabi Vandechali
Abstract
Introduction One of the most important problems arising with operation of the conventional rototillers is severe vibration of the machine handle which is transmitted to the user’s hands, arms and shoulders. Long period exposure of the hand-transmitted vibration may cause various diseases such as ...
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Introduction One of the most important problems arising with operation of the conventional rototillers is severe vibration of the machine handle which is transmitted to the user’s hands, arms and shoulders. Long period exposure of the hand-transmitted vibration may cause various diseases such as white finger syndrome. Therefore in this study, vibrations of a new type of rototiller with ridged blades were investigated at the position of handle/hand interface in different working conditions. Finally, the maximum allowable exposure time to the rototiller users in continuous tillage operation was obtained according to ISO 5349-1. Materials and Methods Experiments were carried out in one of the farms with silty clay soil texture, located in Sari city, Mazandaran province, Iran. Vibration measurements were performed according to ISO 5349-1 and ISO 5349-2 standards in two different modes, including in situ mode and tillage mode. Vibrational parameters were obtained in three blade rotational speeds, i.e., low speed (140-170 rpm), medium speed (170-200), and high speed (200-230). Blade rotational speed varied by changing engine speed using the throttle control lever. In each experiment, different vibrational values were individually recorded in three directions (x, y, and z). Experimental design and data analysis were performed in a Randomized Complete Block Design with three replications using the SPSS16 software. Results and Discussion Based on the obtained results in this study, the RMS of acceleration increased by increasing in rotational speed for all of the conducted experiments. The reason is that number of cutting per unit of time and consequently the frequency of changing in the dynamic forces exerting on the blades dramatically increases with increasing the rotational speed of the blades. Noteworthy is that in most cases the variation of acceleration in the tillage mode showed similar trend with vibrational values in the idling mode. This represents a significant contribution of the combustion engine in vibration of the examined rototiller. Meanwhile, contribution of the engine in the total measured vibration was more than 50% at different rotational speeds and different directions. The minimum engine contribution was measured equal to 56.39% in z-direction at 155 rpm, whereas the maximum engine contribution was observed equal to 79.5%, in x-direction and rotational speed of 215 rpm. These results indicate the importance of selecting a proper combustion engine for reducing the rototiller vibration. It should be noted that the contribution of the engine in total vibration reached its minimum value at the speed related to the maximum generated torque, i.e., 185 rpm of the rotor speed. This result indicates that using the combustion engine in its optimum speed reduces the entire device vibration in the vertical direction. By increasing the rotational speed of the blades in the y-direction, engine contribution in device vibration showed different trends in compare to the other directions. The most value was equal to 74.25% which was obtained at the rotation speed of 185 rpm. By increasing blade rotational speed from 155 rpm to 215 rpm, the engine contribution in device vibration in the z direction and the total acceleration steadily increased. Conclusion With growing mechanization and entering various types of machines to the farm, importance of considerations to human health is also increased, especially in working with rotational machines. Therefore, the current study was undertaken with the specific attention to the rototillers operational vibration at the handle/hand interface. Results of the conducted experiments showed that vibration of the examined rototiller depends more on the operation of the mounted combustion engine, rather than the soil working blades. Therefore, it is suggested to select a higher quality engine with less vibration or isolate the engine from chassis by a damper (such as a compressed rubber) to reduce the vibration transmitted to the operator’s hands and arms.
H. Gholami; D. Kalantari; M. Rajabi Vandechali
Abstract
Introduction Recently, employment of rotary tillers has been expanded in gardens and small farms, especially in the northern of Iran. However using the L-shaped blades in the conventional rotary tillers have some problems such as severe vibration problems, weeds stucking around the blades, forming the ...
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Introduction Recently, employment of rotary tillers has been expanded in gardens and small farms, especially in the northern of Iran. However using the L-shaped blades in the conventional rotary tillers have some problems such as severe vibration problems, weeds stucking around the blades, forming the plow pan and lower performance due to the less powers of such small rototillers. Therefore in order to overcome the above mentioned problems, a rototiller with new ridged blades was designed, fabricated and tested in this research. Materials and Methods Experiments were carried out in one of the citrus orchards in Mazandaran, Sari. The experimental design was split plots based on randomized complete block design with three replications. The soil moisture as main plot varied in two levels of 13.5-21.9 and 21.9-30.3 percent based on dry weight and the rotational speed of blades as subplots varied in three levels of 140-170, 170-200 and 200-230 rpm. The measured parameters consist of soil particle mean weight diameter, soil bulk density, soil crumbling percentage, specific fuel consumption and machine efficiency. The diameter of soil particles was measured using a set of standard sieves with diameter ranging from 0.5 to 8 mm. Then a laboratory shaker was used to sift the samples. Each sample was shaken in 30 sec. The fuel consumption during the experiments was determined by the filled fuel tank method. Analysis of variance (ANOVA) and mean comparisons and interaction between the parameters were performed using the SPSS 16 software. Results and Discussion The results indicated that the soil particle mean weight diameter reduced by increasing blades rotational speed in both examined soil moisture contents. Results indicated that the soil crumbling percent increases with increasing the rotational speed. The main reason for this effect could be due to the more energy transferring to the soil at higher rotational speeds, which result in further crumbling of the soil slices. Regarding the results obtained in this study, the specific fuel consumption increased at first in a light slope, then in a steep rise with increasing the blades rotational speed. The reason can be the higher crumbling percent of the soil at higher rotational speeds and higher soil moisture contents (at the range of 21.9-30.3%), providing the more specific energy consumptions. The specific fuel consumption was the maximum at higher soil moisture content of 30 %. The results indicated that the blades rotational speed and soil moisture content had no significant effect on the field efficiency of the examined rototiller. The field efficiency varied in the range of 92 to 97% in all of the experiments, i.e., rotational speed between 140 to 230 rpm and moisture content ranging from 13.5 to 30.3%. The reason for that was due to the roughly similar turning times, minor adjustments, changing operators and some other parameters influencing the field efficiency. Reduction of the rotational speed of the rototiller from high-to-moderate speeds leads to decrease the fuel consumption to 17 liter ha-1, which could be significant in wide scale of soil tillage operations. As a general result, reduction of the rotational speed had some considerable advantages such as reducing power requirements, reducing blade wearing and maintaining soil structure. Conclusion Influence of soil moisture and rotational speed of blades on the soil particle mean weight diameter, soil crumbling percentage and specific fuel consumption were significant (P<0.01) for fabricated rototiller with new ridged blades. Statistical analysis indicated that the soil crumbling percentage and specific fuel consumptions increased linearly with increasing the rotational speed of blades. The determination coefficients of the crumbling percentage and specific fuel consumption as a function of rotational speed were 0.996 and 0.860, respectively. Meanwhile, clod mean weight diameter decreased linearly by increasing the rotational speed with a determination coefficient of 0.990. For achieving fine soil aggregates, combining high rotational speed and higher soil moisture (20 to 30%) is suggested, while to obtain a coarse soil gradation, low rotational speed and low soil moisture are more suitable compositions. The use of high rotational speed is not recommended due to increasing fuel consumption and consequently the soil erosion and environmental issues.
