دکتر حمیدرضا قاسم زاده

The nut sunflower is usually cultivated in small farms and is harvested with a low capacity of harvester at high moisture content. For the rigid threshing components, impact and knead force are so large as it leads to crushing of the grain or inner stress. This reduces marketability and the germination rate of seeds. The mechanical damage degree of sunflower grain is influenced by the material of the threshing beaters, the velocity of impact, moisture contents, etc. Traditional manual methods, that separate grain from the sunflower head, take a lot of time, require large manpower, have high grain damage, and low efficiency. The objective of the present work was to develop and optimize a threshing unit for nutty sunflower that would combine safe impact velocities with appropriate adjusting of its variable to maximize threshing efficiency whilst minimizing grain damage resulting from shearing, cracking, or crushing.

The nutty Sunflower heads were procured from the Experimental Orchard of University of Tabriz, Iran at the moisture content of harvesting. Axial threshing units using kinematic equation and properties of the grain, designed and constructed that the variables of its components are adjustable. The beater of the thresher is flexible, which the deformation and vibration undergoing the overall rotation and impact process becomes larger with increasing speed and prevents grain damage. The power required for threshing and separation grain from heads was calculated at about 4.5 kW. Diameter and rotational drum speed value estimated using relation (V=  and study of other researches as considering critical impact velocity of sunflower grain. The length of the thresher was 1.2 m that estimated by determining the capacity and the number of beaters. Threshing efficiency (%), separation efficiency (%), and grain damage (%) were parameters of performance for study. The experimental design by the Response Surface Methodology in Design Expert software 11 with central composite experiment design developed and the affecting parameters on accuracy analyzed and optimized. The threshing unit was evaluated against three threshing drum speeds of 380, 280, and 180 (rpm), feed rates 4000, 3000, and 2000 (kg (head)h-1), moisture content of 60%, 45%, and 30 (%w.b).

The results showed that the models and effect of variables were statistically significant at the 95% confidence level. The moisture content on threshing efficiency and grain damage had the greatest effect followed by drum speed and feed rate. While for separation efficiency, the feed rate had the most influence. With reducing feed rate and moisture content the threshing efficiency increased, although the decrease in drum speed reduced it. This might be due to sunflower grains adhering loosely to the head at the low moisture contents. The maximum (99.81) and minimum (96.12) percentage of threshed heads was at the moisture content of 30 and 60, respectively. The separation efficiency increased with reducing of feed rate and moisture content. Though, drum speed had insignificant efficacy statistically. The sunflower heads with high moisture content are fragile and brittle, also at high feed rates, the number of impact forces and collisions of heads rises in the condition of threshing. Therefore, the extra MOG is produced and passed from the separator grille. The feed rate of 2000 kg h-1 and moisture content of 30% was the maximum point of separation efficiency that obtained 69.82%. The grain damage decreased significantly with reducing drum speed (380 to 180) and moisture content (60 to 30). This result may be due to the reasons that at higher moisture content the husk of grains becomes soft. The goal of optimization is maximizing threshing and separation efficiency and minimizing grain damage that the optimized values of variables were determined 292.134 rpm for drum speed, 2000 kg h-1 for feed rate, and 30.7406% (w.b) for moisture content.

A threshing unit of sunflower, using properties of grains and kinematic equation, was designed and constructed. The models and effect of the variable were statistically significant on performances. The moisture content had a greater effect than other factors on threshing efficiency (%) and grain damage (%). Also, the feed rate of crops in thresher had the most influence on separation efficiency (%). With decreasing the moisture content, threshing and separation efficiency increased and grain damage reduced. The threshing efficiency (%), separation efficiency (%), and grain damage (%) were reported in the range of 96.12 to 99.81, 57.34 to 68.55, and 0.49 to 1.25, respectively. The optimized points were determined at the drum speed of 292.134 m s-1, feed rate of 2000 kg h-1, and moisture content of 30.7406% (w.b).

Bread is one of the most important food sources for consumers, especially in developing and underdeveloped countries. Large quantities of bread are wasted every year because different factors affect the number of waste products include flour quality, bread production technology, and the storage condition of the bread. Among the factors affecting the quality of the flatbread, technological factors including the source and method of heating the dough and the type of baking bed are very important. Those factors affect the quality and staleness of the bread and the amount of energy consumed per ton of the produced flatbread. All of these issues depend on how heat and mass are transferred. At present, for the baking of the flatbread, direct heat transfer of the burner (torch) to the dough is utilized in the Iranian bread industry. The use of the direct heat method in baking causes non-uniform heat distribution and non-uniform baking of the flatbread. Also, it causes the deposition of some chemical compounds such as benzopyrenes on the surface of the bread due to incomplete combustion of fuel and gases from the burning process of fossil fuels. At present, the change in the structure of bread production from traditional methods to industrial methods is one of the most important factors in the production of safe and standard bread while improving its quality. The objective of this study was to improve existing systems and developed the new flatbread industrial baking machine to increase product quality and product storability.

The design and construction of the oven were performed based on the existing machine in the bread industry. The final dimension of the bread baking machine was 250 ×250 cm, a height of 160 cm. Rotary bread baking machine with an indirect heating system was designed and heat exchangers of the machine were simulated. The uniformity of airflow velocity inside the exchangers and the distribution of heat on the dough on the baking bed were investigated. After achieving the most effective design, the exchangers were constructed and installed inside the baking machine. A rotary baking bed was constrained with cast iron with a diameter of 220 cm and a thickness of 18 mm that was able to rotate horizontally. A three-phase electric motor with a speed of 1400 rpm and a power of 1.5 kW was used for the rotation system of the bed and carousel assembly. Two heat exchangers with an optimized shape were constructed with SS310 coupled with 2 burners. Bread baking experiments with the developed machine and the existing conventional machines were conducted to evaluate the sensory and staling characteristics of the produced flatbreads from different baking machines.

The simulation results indicated that the air velocity in the center of the middle pipes of the upper exchanger with a standard deviation of 0.05 was in the range of 1.552 to 1.72 ms-1, which means an acceptable uniformity. In the lower heat, there was a relatively uniform air distribution. The experimental validation of the developed simulator indicated that there is good agreement between the measured and predicted air velocity. In the top exchanger, R2 and RMSE were 0.9 and 0.36, respectively and in the top exchanger, they were calculated to be 0.97 and 0.218, respectively. The results indicated that the sensory qualities of the bread produced with the indirect heating system in the present study as well as uniformity of baking and sensory acceptability were superior compared to the bread produced from the conventional industrial machines with direct heating systems (with a total sensory score of 5.09 vs. 4.54). Mold was also observed in a few breads, with direct heating samples, after 168 hours of storage. However, no significant changes were observed in the quality of the bread cooked by direct heating methods after 48 hours of storage, and this type of flatbread lasted more than 168 hours without mold. It should be noted that mold is one of the most important quality deterioration factors and its weight in the quality assessment of the bread is greater than the other quality evaluation factors even though it has not been included directly in the evaluation standards. If the bread becomes moldy, it will be unsafe for consumption and fully wasted. Accordingly, the flatbread produced by the indirect heat was the best choice for long-term storage purposes and the reduction of food waste. Another feature that was evaluated in the bread was the uniformity of baking of all parts of the flatbreads. One of the main problems with the industrial direct heat baking machines is the fact that the outer edges of the flatbread burn due to the inadequacy and somehow incompatibility of the exchangers with the baking space, the dimensions of the flatbread, and incorrect design of the heat exchangers. The flatbread baked with indirect heat and the newly designed exchangers was very uniform with no signs of burning in the outer edges of the bread.

In general, the results of the current study indicated that the use of the simulation tools, the design and manufacturing of the new exchangers and uniform indirect heating of the baking bed resulted in the production of higher quality bread which could be stored for a longer period of time while reducing the food waste. Also, bread prepared using the new machine was free of any contaminants such as PAHs.

Bread is one of the main categories of food in Iran that supply daily calorie, protein. Lavash flatbread consisted about 34% of total flatbreads produced in Iran. Large quantities of bread are wasted every year because bread production technology and baking methods. The main objective of this study was to evaluate the flatbread quality produced by the developed bread baking machine with an indirect heating system and the existing conventional machines with a direct heating system. Bread baking experiments were conducted and the instrumental, sensory, and staling characteristics of the produced flatbreads was evaluated. The effect of baking methods and storage time on the quality of bread was significant and the bread produced with the indirect heating system had higher rating compared to the bread produced from the conventional industrial machines with direct heating and its shelf life was longer. In the indirect heating machine, there was acceptable uniformity on the baking bed as view point of heat distribution and baking uniformity. The variation of puncher force of 10 mm probe in the 5 layers of bread indicated that the surface firmness of bread increased after 48 h of storage. In addition, in the first days of storage, no differences was observed in the puncher force of bread produced by two machines but during the storage, the firmness of breads produced by indirect heating machine was lower as compared with direct heating machine. Also, bread prepared using the new machine was free of any contaminants such as PAHs.

The growth of livestock production and the development of livestock farms increases the production of by-products, including livestock waste, which leads to destructive environmental effects. Paying attention to waste management methods has a beneficial effect in reducing the amount of environmental effects. The present study was performed by practical data collection from 4 farms with different methods of waste disposal. The tables and recommendations of the Intergovernmental Panel on Climate Change (IPCC) were used to estimate emissions levels. The obtained data were processed with Simapro software to calculate the environmental indicators of disposal methods. Based on the results, in the management method of waste collection in lagoon, the final environmental index was the lowest as 0.706 per ton of waste. In the depot method for dry mass and using part of it as animal bed, the obtained index was the highest with 1.379. Among the environmental effects and indicators, the effect of the global warming group in all farms was greater than the effect of other groups. Despite the high production of methane in the storage method in the lagoon, due to the production of nitrous oxide gas in the drying method and especially the use of dry waste in the animal bed, these methods had a greater effect of global warming. By managing waste through anaerobic digestion and methane collection, environmental effects can be reduced and energy benefits can be used.

 In this research, some parameters affecting walnut kernel extraction quality under impact loading were studied. The tests were carried out on the available genotypes in Iran. For this purpose, three different genotypes from walnut orchards of Azarshar city were selected and the total yield of these genotypes was collected. The universal test machine (Hounsfield) was used for the compression tests. For the impact tests, four factors were evaluated in a factorial experiment using a completely randomized design with five replications. The factors were genotype, moisture content, load direction with three levels, and compression speed (three levels), and the effect of these factors on kernel extraction quality was studied. Walnut breakage assessments and kernel extraction quality were evaluated by well-defined criteria. Generally, with increasing moisture content, the percentage of broken kernels decreased and the extraction quality grade was improved. The percentages of broken kernels increased when compression speed was increased. Generally, soaking the walnuts in water for 12 h and Y loading direction yielded the best kernel extraction quality.

In this research, some parameters affecting walnut kernel extraction quality under impact loading were studied. The tests were carried out on the available genotypes in Iran. For this purpose, three different genotypes from walnut orchards of Azarshar city were selected and the total yield of these genotypes was collected. The universal test machine (Hounsfield) was used for the compression tests. For the impact tests, four factors were evaluated in a factorial experiment using a completely randomized design with five replications. The factors were genotype, moisture content, load direction with three levels, and compression speed (three levels), and the effect of these factors on kernel extraction quality was studied. Walnut breakage assessments and kernel extraction quality were evaluated by well-defined criteria. Generally, with increasing moisture content, the percentage of broken kernels decreased and the extraction quality grade was improved. The percentages of broken kernels increased when compression speed was increased. Generally, soaking the walnuts in water for 12 h and Y loading direction yielded the best kernel extraction quality.

According to reports on trends in the agricultural industry, demand for more precise and affordable machinery is rising and precision farming methods used by farmers are expanding. Damping vibration of the boom sprayer is one of the challenges for researchers when crossing the surface roughness. The lack of uniformity of the nozzle spray pattern and the reduction of the precision and quality is the result of an uncontrolled vibration of the boom sprayer. So far, many efforts have been made to decrease the vibration of the long sprayer boom. Using active and passive methods, researchers have achieved great success in reducing the spray boom vibration. Many of these methods are based on the use of external force as a controlling force. Expensive equipment, the use of tractor hydraulic power, and high energy costs are the main disadvantages of these methods. In the present work, a new system called "variable support" was designed and built. The boom rests on a round bar at its midpoint; as the boom tends to oscillate, a minute amount of rotation of the bar activated by a servomotor in an appropriate direction, alters the position of the resting point of the boom on the supporting bar, bringing the boom back to its initial balanced position as a result.

To carry out experiments, the universal tractor U650 and a mounted tractor sprayer model tms500 with 8 m boom and a 500-liter tank, was used in this research by making changes to the design of the simple tractor sprayer a new active sprayer designed and built with intelligent online balancing system that in addition to balancing the boom angle, it reduced the fluctuations that occur during work. Electronic control was used to control the position of the boom. The microcontroller programming codes were developed and uploaded in the microprocessor to execute instantaneous commands to the mounted activator due to the need for boom positional data for analyzing experiments, a data logger was also designed in conjunction with the controller circuit and the algorithm was loaded after coding with C++. To compare the new sprayer with the conventional, a field test was conducted. Tests were carried out according to manufacturer's instructions at three-speed levels of 3 (low), 5 (medium), and 8 km h-1 (high), with three bumps heights of 10, 15, and 20 cm with three replications. For the acquisition of vertical acceleration as well as axial rotation data in the conventional sprayer, a data logger with an accelerometer and gyroscope was used. The data logging rate and the accuracy of the accelerometer and gyroscope measurement were set to 50 Hz, 0.1 m s-2 and 0.1°, respectively.

To compare the behavior of the active and the conventional spray booms in terms of vibrations, the univariate analysis was used. The results showed that there was a significant difference between the performances of two sprayers at 5% probability level with the sig. number of 0.000.To compare the behavior of the active and the conventional spray booms in terms of axial rotation, also the Univariate analysis was used. The results showed that there was significant difference between the performances of two sprayers at 5% probability level with the sig. number of 0.000. Also, comparing the marginal mean values of the data obtained from the data logger showed that the active boom compared with the conventional boom had less axial rotation and less vertical acceleration.

Results of experiments showed that the new sprayer with variable support system, relative to the conventional sprayer in terms of controlling boom acceleration and the angular balance of the boom with a significant difference had relative superiority and can be considered as an appropriate alternative to increase the accuracy of spraying, although more research on large scale booms are necessary before coming to final conclusion.

One of the most time-consuming and difficult stages of crop production is the harvesting stage, that almost more product losses occur at this stage. Adjustments are very important in increasing the efficiency of grain combine harvesters and subsequently decreasing product loss. However, good adjustments require the identification of the components of the harvester, quantifying the losses in these components. In this research, a model has been developed to measure the rear losses of combine harvester (total threshing and separation losses) based on machine parameters. In this research, the effects of different levels of forward speed (3, 4 and 5 km/h), cylinder rotating speed (1100, 1200 and 1300 rpm) and fan speed (600, 700 and 800 rpm) on rear losses of combine harvester in three replications were investigated. A factorial experiment based on a randomized complete block design generally results of ANOVA showed that the travel speed, cylinder rotating speed and fan speed had significant effect on rear loss. Multivariate linear regression was used to make model and determine the relationship between rear loss and investigated parameters. The results of the regression model analysis showed that there was a good fitting between the rear loss and the parameters at the probability level of 1 or 5%. In other words, this model can be used for prediction of combine harvester rear loss under different operational conditions. The coefficient determination of model was obtained 0.85, which shows that a significant part of the rear loss of combine harvester is justified by the three parameters examined in this study.

Previous studies have indicated the positive impact of dietary supplementation of arginine on meat quality and growth, though there is no report regarding the effect of in ovo injection of arginine on meat quality. So, the aim of this study was to evaluate the effect of in ovo injection of different levels of L-arginine on hatchability, growth performance, and meat quality of Ross 308 broiler chickens. In this research, 300 fertile eggs were used in a completely randomized design with three experimental treatments (levels of 0.5 and 1% of L- arginine and total control). Experimental groups included: 1) in ovo injection of 0.5% L-arginine, 2- in ovo injection of 1% L-arginine, 3) total control group {collected control 1 (injection of distilled water) and control 2 (no injection)}, which were injected on d 14 of incubation. After hatching, broiler chicks of arginine treatments and total control group were divided each into four equal groups and placed randomly into four cages (replicates of the experiment). The rearing period continued from hatching to d 24. In order to investigate the quality of meat, on day 24, three chicks from each replicate (12 chicks per each treatment) were weighed, slaughtered and their breast muscles were used for meat quality evaluation. Based on the results, in ovo injection of different levels of L- arginine did not significantly affect 1, 10 and 24 day-old birds’ weight, daily weight gain, feed intake, feed conversion ratio, and relative weight of scalped carcass and breast muscle (P >0.05). Although, meat pH, meat fat and Ash content, and meat color indexes (a*, b*, L*, H) were not affected by L- arginine in ovo injection treatments (P>0.05), meat water loss, ΔD, and C indexes were significantly affected by experimental treatments (P˂0.05). Based on the overall results of this study, in ovo injection with different levels of L- arginine could not have a significantly noticeable effect on growth performance, meat production and/or meat quality of 24 day- old broiler chickens.

 Cereals are one of the strategic products and each year a large area of ​​agricultural land is dedicated to their cultivation. Cultivation of cereals is considered to be the main agriculture in Iran. One of the most sensitive and difficult stages of cereal production is the harvesting stage almost more product loss occurs at this stage. Forward speed, cylinder rotation speed and blower rotation speed of Harvester are important operation parameters that affect harvester losses. In order to evaluate the effect of these parameters on total grain loss, this studying was conducted in 3×3×3 factorial pattern with randomized blocks design. The independent variables in the experiments were forward speed (3, 4 and 5 km/h), cylinder rotating speed (1100, 1200 and 1300 rpm) and blower rotating speed (600, 700 and 800 rpm). For a real evaluation, these factors and their levels were chosen based on operators’ experiences. The experiments were done in Moghan Agro-Industrial & Livestock Co. (MAIL) with CLAAS combine harvester (Tucano 320 model).  The results of this study showed that the minimum loss related to the 4 km/h, 1300 rpm and 800 rpm for forward speed, cylinder rotation and blower rotation speed, respectively.

Increase of municipal waste which mainly consists of domestic waste and, in other words, environmentaly biodegradable materilas, pose serious challenges to the selection of efficient disposal methods every year. Lack of comprehensive data set as well as uncertainty in some cases make decision making on waste disposal method selection more complicated and requires a more efficient waste treatment system.
In this study, the hierarchical analysis process was used to assess and prioritize waste disposal methods. Considered methods were: composting, incineration, segregation and sanitary landfilling of urban waste. The criteria for evaluation of options included: waste synthesis, environmental issues and costs.
According to the results obtained from analysis of collected information, environmental issues with the relative value of 0.778 were the most important criterion to be considered. Finally, the waste segregation and sanitary landfilling with the absolute value of 0.444 proved to be the best option. Compost production and incineration methods were ranked next, respectively. The inconsistency rate for all comparisons was 0.1 which is considered acceptable.
Considering the small difference between the final values obtained for sanitary landfill and compost production methods, both should be studied more closely. The studies on waste synthesis in different parts of the country confirm the findings of this study.

Since suitable speed must be selected for every work especially in agricultural activities, feasibility of achieving different speeds by operator under the intended conditions is one that companies take into consideration. These speeds include: creep speed, slow speed, farm speed and transport speed. This study aimed to redesign the gearbox of ITM285 to produce a gearbox which can provide the operator with creeping speed besides the span of speeds already existed. After necessary calculations, the kinematical diagram was prepared, the ratio and size of gears were figured out, and the loads on the gears were examined. Both theoretical and software methods were used for calculate and analysis, and the required modifications were made in dimensions. The involute spur gear was drawn using Geartrax2008, modeled in Solidworks2008, and the analysis was made using Ansys11.0 and Cosmos2008. The loads on the pins and shafts in different gears were calculated and examined in terms of their strength to stand for bending and torsion stresses. Considering the restrictions on redesigning and applying the maximum possible modifications on the dimensions and technical specifications of gears in ITM285 gearbox, it was shown that only making some modifications in the gearbox is not enough to achieve creep speed. Using the final driver of ITM399 with the reduction ratio of 4.8 was thus suggested so that the forward speed of 1.2 km/h was achieved

In the present work, the rheological properties of two varieties of tomatoes were studied under creep recovery test. A factorial experiment in the form of completely randomized design was used to determine the effects of storage time and variety on the viscoelastic properties. The results showed that 4-elements model (Burgers model) can explain the rheological behavior of the products with highest determination coefficients. The variety had a significant effect on the coefficients of elasticity, viscosity and retardation times at 1% level of probability. The values for the mentioned parameters in Shaghayegh cultivar was greater compared to that of Ergon cultivar. Also, the elastic modulus values increased with increasing storage time, where the values for the coefficients of viscosity and retardation times reduced at the same time.

In this research the quality of walnut kernels under impact loading were studied. Due to unavailability of specific varieties of walnut in Iran, the tests were carried out on the available genotypes. Three different genotypes from walnut orchards of Azarshar region were selected and were collected in 2009. A drop test device was designed and constructed to perform the experiments. The impact tests were performed considering five factors in a factorial experiment using completely randomized design with five replications. The factors were genotype, moisture content, geometrical mean diameter, load direction with three levels and the hammer drop height (five levels). The effect of these factors on kernel quality was examined. Walnut cracking assessments and kernel quality were evaluated by well-defined criteria. Generally, by increasing the moisture content, the percentage of broken kernels decreased while the number of unbroken kernels increased and the quality grade of the kernels improved. The percentage of broken kernels increased as hammer drop height increased. Soaking the walnuts in water for 3 hours, with transverse loading (in Y direction) and hammer drop height of 35cm were formed the best set of walnut cracking parameters for obtaining quality kernels.

Simulation of the heat and moisture transfer is one of the effective techniques for modification and optimization in different food drying methods. One of the most important factors to improve the accuracy of the predicted temperature and moisture content profiles in a drying process is the shrinkage or volume reduction of products The aim of this study was mathematical modeling of the shrinkage rate and the moving velocity of product boundary during drying process in order to prediction of slices thicknesses and the distance of inner nods using numerical solution for related function by finite element method. The drying of apple slices was conducted in the air velocity of 0.6, 1.2 and 1.8 m s-1 and the temperature of 50, 60 and 70 ºC. Based on the results, the thickness of the samples reduced from 0.0053 to 0.0014 m. The exponential model showed a better fitness to the results for thickness and boundary moving velocity change in compare to the other studied models. The model coefficients were calculated as a function of drying time, temperature and velocity of hot air. The distance of domain internal nods was predicted as a function of outer boundary velocity and drying time. A good fitness was observed between the experimental and simulation results in sample shrinkage.

In the present research، the physical، nutritional and chromatic properties of strawberry (Fragaria x ananassa)، Selva Cultivar were studied. The values for mass، diameter، length، geometric mean diameter and sphericity of strawberry fruit at 91. 07% moisture content (d. b.) were 11. 885 g، 28. 260 mm 29. 697 mm، 28. 585 mm and 0. 971 respectively. At the same moisture content، volume، true density، bulk density، porosity and hardness were 12. 325 cm3، 1068. 880 (kg/m3)، 474. 330 (kg/m3)، 51. 11%، 8. 606 cm2 and 3. 632 N respectively. Static coefficient of friction on the steel، galvanized iron، plywood and rubber surface measured as 0. 415، 0. 439، 0. 473 and 0. 575 respectively. Analysis of variance showed that there was a significant difference between the surfaces of various materials and only galvanized steel and iron surfaces were not significantly different. The color parameters L*، a*، b* and color intensity were 29. 6، 29. 7، 28. 2 and 40. 95، respectively. The values for pH، TSS، total acidity، vitamin C، dry matter and ash were 3. 6، 7%، 3. 8%، 64. 13 (mg/100g)، 8. 90 (mg/100g) and 0. 787 (mg/100g)، respectively.

In the present research, susceptibility of two strawberry cultivars (Selva and Gavita) to bruising was studied. Individual fruits were subjected to impact and compressive forces. Impact forces were applied through dropping the fruits from predetermined heights as well as pendulum. Bruising volume was considered as damage index. In both methods bruising severity was increased as a function of impact energy. Dropped fruits were showed higher bruising volume than those of fruits impacted by pendulum for similar energy levels. Increasing energy level by a factor of four (from 0.022 to 0.082 J) caused the bruise volume to increase by a factor of three (from 46 to 134.5 mm3). Increasing drop height from 18 cm (0.026 J) to 54 cm (0.079 J) caused the bruise volume to increase up to 35%. Bruise severity due to compression force was higher than those of obtained from other tests. Doubling the loading time from 2 to 4 seconds showed no significant difference in bruise volume. Although Gavita variety had greater sensitivity to bruising than Selva variety, the effect of variety was significant only in impact test with pendulum tester.

Energy is an important input in agriculture and harvesting operation of grain crops constitutes a major part of total energy input. Hence, calculation of power consumption for this operation to minimize power loss is essential. In the present research, an appropriate model for calculation of Sahand 68s combine power requirement was given and the the power consumption of the combine for harvesting of wheat (Alvand variety) in Tabriz was calculated. In the proposed model, geometric as well as functional parameters along with crop conditions were considered. For the purpose of power consumption calculation it is necessary to determine power consumption in combine's individual components such ates reel, cutter bar, platform conveyor, feeder conveyor, thresher, straw walker, blower, sieves, grain-conveying unit, tailings feed unit, traction unit and bearing friction energy losses in different parts. Results showed that the total power consumption of Sahand 68s combine for harvesting of wheat (Alvand variety) in Tabriz is 88.472 hp. Calculations also indicated that threshing cylinder with 54.035 hp was the highest power consuming unit among the working units of the combine followed by traction, straw walker, cutter bar, reel, blower, sieves, grain-conveying unit and finally feeder conveyor with 0.0217 the lowest.

In any production system, if operations such as sowing and harvesting are not accomplished on time, reductions on yields and/or product quality can be expected. Alfalfa mechanization projects similar to other production systems need precise scheduling, planning and management. The basic approach of all scheduling techniques is to form a network of activity and event relationships that graphically portrays the sequential relations between the tasks in a project. Such a network is a powerful tool for planning and controlling a project. It is a consistent framework for planning, scheduling, monitoring, and controlling the project. In this research, GERT Networks were used, because GERT is a powerful tool for the system analyst since it has all the advantages associated with networks and provides an exact evaluation of certain types of networks. With GERT Networks, mechanization project of alfalfa production was simulated and modeled the network before analyzing. Results showed that the network model was able to answer any statistic al the questions concerning the project. Networks model, particularly GERT networks are increasingly be coming a powerful tool for modeling, scheduling, planning, controlling and analyzing of agricultural mechanization projects