نشریه ماشین های کشاورزی
سال چهارم شماره 2 (پیاپی 8، نیمسال دوم 1393)

In this paper، a low-cost dynamometer for rolling، steered wheels is described. The dynamometer was constructed to determine whether such an instrumented mechanism was practical. Four S-beam load cells، an Opto-counter and a potentiometer were used to obtain all moments، and forces using dynamic and kinematic analysis. Minimal simplifying assumptions considered for the required calculations. Overturning، aligning and rolling resistance moments besides vertical force are directly measured by the load cells. The Opto-counter detects wheel angular velocity and the potentiometer was used to measure the steering angle. The results showed that the mechanism was very well calibrated with a coefficient of determination of over 0. 99 and can be used to define wheel dynamic behavior.

Automation of tractors due to their widespread use in different sectors e. g. agriculture، construction and industry have been seriously considered by researchers. In this study a tele-steering system for tractor was designed and constructed to controling and steering so the operator can control the tractor even far away from the stressful condition of tractor cab،. A CCTV camera and an electric motor were used in order to view the path and to rotate the steering shaft accordingly. Bilateral communication between the control center outside the tractor and control unit on the tractor was provided by a Wireless Local Area Network (WLAN). To evaluate the effect of relevant parameters on system performance camera position، steering shaft rotational speed and tractor ground speed were selected as experimental factors in a completely randomized design. Root mean square of error (RMSE) of lateral deviations and frequency of out of range around the reference route (Nout) were used as criteria in variance analysis. The results for two different ground surfaces with three replications showed that the performance of system had less sensitivity on soil surface and had better stability because of deformable structure and condition of soil compare to asphalt. Steering speed alone had no effect on the accuracy of tractor guidance. This is because the accuracy of the system mainly depends on capability، skillfulness and mental concentration of the operator. The position of the camera installed in front of the tractor had higher accuracy than that of rear camera. Moreover، by increasing ground speed the RMSE of lateral deviations and Nout increased and this is in agreement with the results of previous research works.

Precision Agriculture is continuously trying to address the sources and factors affecting the in-field variability and taking appropriate managerial decisions. One of the popular research focuses in the recent three decades has been on the development of new approaches to making yield variability maps. Advancement in development of sensors and the importance of quality factor in high value crops has motivated scientists to investigate real-time and nondestructive testing methods. This study tried to introduce and evaluate a new approach to concurrent yield mapping and to estimate some nutritional qualitative factors of alfalfa production. In this study، yield quantity was determined by measurement of added hay slice in every hay compression cycle by employing a new star wheel and integrating its output with positioning data from Global Positioning System. To predict some nutritional quality properties، measurement of specific shear energy applied on the cutting blade and compressive energy on plunger head of a hay baler in field conditions were also evaluated. The results of statistical analysis of yield quantity measurement data showed a very good correlation between the suggested approach and yield mass (r=0. 96 and R2=0. 92). The results of using specific shear energy for estimation of crude fiber and cumulative index RFV with regard to field conditions were rated as acceptable. Using specific compression energy was suitable only for estimating the dry matter. None of the suggested methods was able to estimate the hay crude protein. Further investigations at more extensive variations of quality indices and alfalfa varieties are suggested.

In conventional cultivation of sugar beet the weeding and crust breaking are mostly performed manually. The objectives of this research were to design، fabricate and evaluate a soil crust breaker and weeding implement equipped with a detecting sensor. Each unit consisted of a distance detecting sensor and a hydro-motor for driving the blades and pneumatic valves for moving the blades. The hydro-motor was activated by the sensors. To avoid damaging the plants، a command signal was sent to the pneumatic valves to move the blades up and down and pass safely. Three configurations of cutting blades were considered which could be mounted to the crust breaker. The field evaluation was conducted with two tractor forward speeds (0. 4 and 1 km h-1) and four plant-to-plant spacings within rows (20، 25، 30 and 40 cm) all with three different blade shapes. For field evaluation split plot experiments arranged in a completely randomized block design with three replications. The number of plants damaged (evaluated only for four-lobe blades) and size of broken crusts (evaluated for all blade shapes) for various treatments were recorded and compared. The results of analysis indicated that the higher the inter-row spacing the lower the injury to the plant. The highest and the least damage to the plants occurred for within-row plant spacings of 20 and 40 cm، respectively. The forward speed was also significantly affected the percent of plant damaged. The forward speed of 1 km h-1 at 20 cm spacing had the most (59%) and the speed of 0. 40 km h-1 at 40 cm spacing had the least effect (3. 3%) on the percent of plant damage. The two-lobe blade could result in the maximum surface area broken.

Overall energy efficiency (OEE) is an important indicator of energy consumption in tillage operations. Tillage energy was studied objectivity to accurately measure the OEE of MF399-4WD tractor. The tractor was equipped with different types of sensors to measure and calibrate the required data including: fuel consumption، actual forward speed، wheel speed and slippage، engine speed، draft and drawbar power. The data were recorded with frequency of 1000 Hz and transmitted by employing a suitable wireless technology in the range of up to1. 5 km to the user''s personal computer and is stored in Excel format. The hardware and the software program، which was written in C# language، simultaneously monitor the changes in functional parameters and the monitoring can be done even from far away and via the Internet. The split factorial experiment with three factors including ballast، selected gear ratio and two wheel drive configurations (two and four wheel drive) was employed to perform analysis of variance (ANOVA)، POST ANOVA AND PATH ANALYSIS. The results show that the performance of remote monitoring devices installation was very accurate and high-quality. Furthermore، statistical analysis showed that three parameters including slippage، fuel consumption and tractor Power Equivalent (PEQ) were the most effective parameters on overall energy efficiency of tractors – tillage. The variance analysis showed that the effect of gear ratio and drive configuration on the OEE were also significant at the one percent level. However، ballasting had no significant effect on the OEE.

Fast pyrolysis is an attractive technology for biomass conversion، from which bio-oil is the preferred product with a great potential for use in industry and transport. Corn wastes (cob and stover) and eucalyptus wood are widely being produced throughout the world. In this study، fast pyrolysis of these two materials were examined under the temperature of 500 °C; career gas flow rate of 660 l h-1; particle size of 1-2 mm; 80 and 110 g h-1 of feed rate. The experiments were carried out in a continuous fluidized bed reactor. Pyrolysis vapor was condensed in 3 cooling traps (15، 0 and -40 °C) plus an electrostatic one. Eucalyptus wood was pyrolyised to 12. 4، 61. 4، and 26. 2 percent of bio-char، bio-oil and gas، respectively while these figures were as 20. 15، 49. 9، and 29. 95 for corn wastes. In all experiments، the bio-oil obtained from electrostatic trap was a dark brown and highly viscose liquid.

The use of Bio-ethanol as an alternative diesel engine fuel is rapidly increasing. Bio-ethanol is mixed with diesel fuel at different ratios and used in CI and SI engines. Since vibrations have direct effects on users and engine components، for this reason analysis of vibration resulting from combustion in CI engines is very important. In this study، evaluation of vibration was performed for both diesel and ethanol blends. Commercial diesel fuel (D100)، E2 (2% ethanol and 98% diesel fuel)، E5، E10، E15 and E20 were used in a two-wheel MITSUBISHI tractor. The engine was tested in 1200، 1600، 2000 and 2400 rpm for all fuel blends، and also the effect of load was investigated for D100 and E10. Results showed that vibration is significantly affected by fuel blend. It was observed that E10 had the lowest vibration while E20 had the highest value. It was also observed that vibration increased as engine speed increased for all fuel blends. It was found that both axial and lateral vibrations affected significantly by load. The lateral vibrations decreased continuously with load rise، but the axial vibrations increased initially but started to follow a reverse trend.

Application of satellite imagery and remote sensing techniques in agriculture and other natural resources has been approved by many studies. In this study two ETM+ imagery data for May and September 2012 of Astan Ghods Razavi Great Farm were acquired to identify the boundaries of lands cultivated with different crops coverage and to create crops maps of that farm.. To classify the images، the supervised classification methods including Maximum Likelihood and artificial neural network were used. In order to compare the results of two applied classification methods، the same training and testing samples were used. To evaluate the accuracy of classification results، the produced map was compared with the ground control points extracted by GPS and local observations. Kappa coefficient and overall accuracy were estimated to be 82% and 85%، respectively by maximum likelihood method and these outputs were estimated to be 84% and 87%، respectively by neural network approach. The difference of cultivated area estimated by maximum likelihood and by neural network methods with actual measured area was 16. 8% and 14. 2%، respectively. The results of this study showed that satellite imagery has high capabilities to classify and estimate agricultural and cultivated areas. These data can be useful for strategic management to develop mechanization and cultivation plans.

Local information about tillage intensity and ground residue coverage is useful for policies in agricultural extension، tillage implement design and upgrading management methods. The current methods for assessing crop residue coverage and tillage intensity such as residue weighing methods، line-transect and photo comparison methods are tedious and time-consuming. The present study was devoted to investigate accurate methods for monitoring residue management and tillage practices. The satellite imagery technique was used as a rapid and spatially explicit method for delineating crop residue coverage and as an estimator of conservation tillage adoption and intensity. The potential of multispectral high-spatial resolution WorldView-2 local data was evaluated using the total of eleven satellite spectral indices and Linear Spectral Unmixing Analysis (LSUA). The total of ninety locations was selected for this study and for each location the residue coverage was measured by the image processing method and recorded as ground control. The output of indices and LSUA method were individually correlated to the control and the relevant R2 was calculated. Results indicated that crop residue cover was related to IPVI، RVI1، RVI2 and GNDVI spectral indices and satisfactory correlations were established (0. 74 - 0. 81). The crop residue coverage estimated from the LSUA approach was found to be correlated with the ground residue data (0. 75). Two effective indices named as Infrared Percentage Vegetation Index (IPVI) and Ratio Vegetation Index (RVI) with maximum R2 were considered for classification of tillage intensity. Results indicated that the classification accuracy with IPVI and RVI indices in different conditions varied from 78-100 percent and therefore in good agreement with ground measurement، observations and field records.

Each year، millions of liters of toxic liquid، are used to combat with pests and plant diseases in farms. The wide spread use of chemical pesticides causes great environmental hazards. Particles drift is one of the main problems in spraying which results in the contamination of farm lands، humans and animals. Management of particle size is regarded as the main factor in drift control. In this study، the effect of some parameters on the size of deposited particles on non-target areas was studied using statistical method. The effects of nozzle type (orifice size)، spraying pressure، spraying boom height and wind speed as effective factors on drift were examined. A horizontal wind tunnel with working section of 0. 47 m wide، 0. 75 m height and 5. 5 m long was used for testing. Experiment was performed in the form of factorial split-plot based on randomized complete block design with two replications. Droplets were measured in the treatment combinations of the type of flat-fan nozzle with three orifice area (11003- 0. 87 mm2، 11004-1. 18 mm2 and 11006- 1. 8 mm2)، spraying pressure (150، 275 and 400 kpa)، wind speed (1، 2 and 3 m s-1) and the boom height of (0. 35، 0. 55 and 0. 75 m). Water-sensitive papers were used at intervals of 0. 8، 1. 6 and 2. 4 m from the tip of nozzles for detecting droplets size. The factors of pressure، speed and height had positive effects on the droplet size at the desired distance، but the effect of nozzle size on droplet size was negative. In the regression model the coefficients of speed was higher than the others.

Crop yield estimation is one of the most important parameters for information and resources management in precision agriculture. This information is employed for optimizing the field inputs for successive cultivations. In the present study، the feasibility of sugar beet yield estimation by means of machine vision was studied. For the field experiments stripped images were taken during the growth season with one month intervals. The image of horizontal view of plants canopy was prepared at the end of each month. At the end of growth season، beet roots were harvested and the correlation between the sugar beet canopy in each month of growth period and corresponding weight of the roots were investigated. Results showed that there was a strong correlation between the beet yield and green surface area of autumn cultivated sugar beets. The highest coefficient of determination was 0. 85 at three months before harvest. In order to assess the accuracy of the final model، the second year of study was performed with the same methodology. The results depicted a strong relationship between the actual and estimated beet weights with R2=0. 94. The model estimated beet yield with about 9 percent relative error. It is concluded that this method has appropriate potential for estimation of sugar beet yield based on band imaging prior to harvest

In this research، four different positioning methods were compared in order to evaluate their accuracy، using a remotely controlled robot on a specific route. These methods included: using a single GPS module، combining the data from three GPS modules، using an Inertial Measurement Unit (IMU)، and GPS/IMU data fusion. The comparison of these four methods showed that GPS/IMU data fusion along with a Kalman filter was the most precise method، having a root mean square error of 23. 4cm. Integrating the data acquired simultaneously from three GPS modules with fixed and equally spaced position and far enough from each other، had a root mean square error of 31. 3cm was the second most precise method.. Also analysis of the IMU data showed that due to cumulative errors، it was not a suitable method using a single IMU for positioning.

One of the nondestructive methods for assessing the internal quality of some fruits is the processing and analyzing the sound signals generated by an impact on the fruit. In this regard determining the location and the suitable impact levels for a certain fruit is required. In this study، the selected Crimson sweet variety of watermelon was used for the acoustic tests by imposing the impact force on samples. Acoustic tests were conducted using two independent variables including impact location (two sides of the symmetrical line of watermelon and the opposite of the stem end) and impact levels (12. 09، 15. 08 and 17. 11 kg mm s-1) on the generated sound signals، to evaluate the stiffness of the fruit. The relation between the acoustic signals and the texture of both peel and flesh was examined using puncture test. The results showed that the variation of location and levels of impact on the obtained values of acoustic tests were significant

Evaluation of mechanical and electrical properties of agricultural products plays an important role in equipment design and optimizing post-harvest operations. Among the crops، tomato and its products are the major processing industries in the world and its economic importance is increasing. Considering the importance of the quality and various post harvesting uses of tomato، the evaluation of mechanical properties including rupture force and deformation and the work done to establish the rupture of two tomato cultivars (Petoearly CH and Newton) were studied under penetration test based on the electrical conductivity. These properties were measured at three levels of 1، 3 and 5 days after harvesting. The evaluated mechanical properties of both cultivars were decreased by increasing the storage time. Interaction of cultivar and time were significant at the 1% level، for all mechanical parameters except the deformation failure in both cultivars. The electrical conductivity of both cultivars was decreased by increasing the storage time. Interaction of cultivar and time on the electrical conductivity of both cultivars were significant at the 1% level. Significant relationships were found at the 1% level between electrical conductivity and mechanical properties except for deformation of Petoearly CH cultivar. Among the mechanical parameters، rupture forces and rupture works of both cultivars were highly correlated with the electrical conductivity.

Development of ultrasound technique has not been progressing for evaluating the internal quality of fruits as fast as that of processed foods. In this research for quality assessment of pear fruit (Shah Miveh variety) an ultrasonic measurement system was constructed to transmit and receive the ultrasonic waves. The apparatus included a pulser-receiver، a pair of 75 kHz ultrasonic transducers with exponential horn، and a computer system for data acquisition and analysis. Several mechanical and chemical properties، including firmness، TSS، acidity، elastic modulus، pH and total dry matter for destructive quality assessment were measured. Velocity and attenuation of ultrasonic waves for nondestructive tests were also measured. The fruit quality levels for the experiment were: unripe، ripe and overripe. The results of tests showed that firmness was the best parameter for measuring fruit quality، as it decreased significantly with ripeness. The effect of ripeness on the velocity and attenuation of ultrasonic waves was also significant. Investigation showed a positive linear relationship between fruit firmness and wave velocity (R2=0. 81). Furthermore، the relationship between fruit firmness and attenuation was exponential and wave attenuation decreased with increasing fruit firmness (R2=0. 895). The Relationship between ultrasonic properties and fruit modulus of elasticity showed that the wave velocity increased and attenuation decreased with increasing elasticity. It can be concluded that the ultrasonic instrument equipped with exponential horns can effectively be utilized for pear quality assessment based on measurement of wave velocity and attenuation.

Grain loss monitors are installed on combine harvester and make it possible to measure grain loss on different parts of the combine. The instrument permits the operator to adjust a proper ground speed to keep grain loss within an acceptable range. In this study a loss monitoring system was implemented to measure grain losses continuously on straw walker and sieves. Two grain loss monitors (KEE and TeeJet) were installed behind the straw walker and the sieves of JD-955 and JD-1165 combine harvesters. Harvesting performance parameters such as combine total and processing losses were then measured. To evaluate the precision and accuracy of the instruments، the measured and monitored losses were compared and investigated. The results of a two-year research showed that the average processing loss of the combine harvesters with 10-12% grain moisture content and 750 rpm drum speed was 0. 82% which is whitin the acceptable range recommended by ASAE Standard No. S343. 3. Furthermore، there was no significant difference between the measured and monitored values of processing loss.

Agricultural mechanization is a method for transiting from traditional agriculture towards industrial and sustainable one. Due to the limitation of natural resources and increasing population we need to have economical production of agricultural crops. For reaching this destination; agricultural mechanization has a remarkable role. So it is necessary to have an extensive view for mechanization، because with the help of mechanization the agricultural inputs such as seeds، fertilizer and even water and soil can effectively be managed for an economical and sustainable production. This study has been carried out in many provinces of Iran. The data of agricultural tractors and cereal combine harvesters were firstly gathered by means of questionnaire. The tractors were categorized in four power levels of less than 45، 45 to 80، 80 to 110، and more than 110 hp. In addition، it was also carried out for cereal combine harvesters; it was in three power levels، i. e. between 100 to 110، 110 to 155 and 155 to 210 horse-power in 3 ages، i. e. less than 13، between 13 to 20، and more than 20 years. Information regarding to cultivation areas، production volume، and yield of main crops gathered from statistics of Ministry of Jihad-e-Agriculture. Then agriculture mechanization level index (hp ha-1) in each province was calculated. Four main crops including irrigated and rain-fed wheat and irrigated and rain-fed barley، which met the required criteria to be used in the model، were statistically analyzed. Correlation analysis was carried out in order to get an effective model between yield of the four main crops in Iran and agriculture mechanization level index. Pearson correlation index showed that there is a direct and significant correlation between these variables. Subsequently، outliers were identified in order to get a model with necessary efficiency to predict the yield through mechanization level index، by scatter diagram and estimating regression lines in 1% probability level. The effective model was estimated with acceptable coefficient of determination 0. 851، after removing outliers.

Farm machinery managers often need to make complex economic decisions on machinery replacement. Repair and maintenance costs can have significant impacts on this economic decision. The farm manager must be able to predict farm machinery repair and maintenance costs. This study aimed to identify a regression model that can adequately represent the repair and maintenance costs in terms of machine age in cumulative hours of use. The regression model has the ability to predict the repair and maintenance costs for longer time periods. Therefore، it can be used for the estimation of the economic life. The study was conducted using field data collected from 11 John-Deer 955 combine harvesters used in several western provinces of Iran. It was found that power model has a better performance for the prediction of combine repair and maintenance costs. The results showed that the optimum replacement age of John-Deer 955 combine was 54300 cumulative hours.

In order to restrain the potential of wind energy، the first step is to determine the wind energy potential. In this study the wind data was used from the three-hour frequency recording of 10-year period (2002-2011). To predict the occurrence probability of each wind speed، the two-parameter Weibull function was used. The goodness of fit test by Chi-Square test showed that the wind speed distribution is not represented by the typical two- parameter Weibull function for all the months. Weibull probability density function has a good fit for eleven months، but for the 9th month of the year (September)، it is not fitted. Thus، four-parameter Weibull probability function has been developed to analyze the wind speed frequency distribution in that region for the mentioned months. The electrical energy consumption of agricultural water wells in the region was also calculated for the desired periods of the year. Energy demand and energy supply were matched. Data analysis was performed using SPSS 18. 0. 0، MATLAB 7. 13. 0. 564 and WIDOGRAPHER 3. 0. 2. The results show that in Broujerd، to exploit the wind energy at all times of the year، it is necessary to have at least 39 turbines of 2300 kW with 99 meters tower. If the desired turbines are used، there will be extra energy and also، agriculture will be continued towards sustainable development.

Rice is a main food for Iranian people and has an important role in providing food security. Regarding the population growth، increase of rice production and reduction of losses have special importance in prevention of rice import. Rice losses in the harvest stage are the highest through the whole production period of this crop and hence the reduction of these losses is necessary. Provision of this purpose depends on on-time harvesting and separation of grains from chaff with the least grain losses، and choosing a suitable harvesting method. The choice of harvesting method depends on various factors in each region; thus، different harvest methods in each region must be compared while conducted in the same conditions. In order to recommend the beast harvest method in Shivan-Chardavol region، three harvesting methods (manually، rice-specific combine harvester and conventional cereals combine harvester) were considered as three experimental treatments and four different parts of this region considered as experimental blocks. The experimental design was randomized complete block design. This study was carried out on Anbarboo variety and the measured factors were: effective farm capacity، percent of total losses، percent of harvesting losses، number of workers and harvesting cost. The results of this study indicated that the total difference of factors was significant at the 1% error level among all treatments. The effective farm capacity in harvesting by cereals combine harvester was more than other treatments. The lowest percent of loss was observed for harvesting by rice-specific combine harvester (2. 32%) and the highest percent of loss was obtained for cereals combine harvester (3. 816%). The manual harvesting method had the highest harvesting cost and the lowest cost was found to be associated with the rice specific combine harvester. Therefore، from the results of this study، the use of this combine harvester is recommended for rice harvesting in this region.