مجله پژوهش های مکانیک ماشین های کشاورزی
سال چهارم شماره 1 (پاییز و زمستان 1394)

In this study, a branch shaker was constructed and evaluated in order to harvest apple (the variety Golden Delicious) and also decrease the oscillatory effects of shaker on the tractor. This system was made in a way that it had the capability of changing the oscillation amplitude in three levels of 20, 32 and 40 mm as well as the frequency in levels between 4-20 Hz. In order to determine the most suitable amplitude and frequency of the shaker on the separation of fruit from the branch, a factorial experiment (3×3) was conducted through a completely randomized design. In this experiment, the effect of three levels of frequency (4, 12 and 20 Hz) and three amplitudes of oscillation (20, 32 and 40 mm) on the separating percentage of the fruit were investigated. The results of variance analysis and comparing averages showed the significant effect of different levels of amplitude and frequency of the fruit on the separation of apple fruit, while the interaction effect of these two factors didn’t show any asignificant effect. 40 mm and 12 Hz were determined as the most appropriate oscillation amplitude and frequency, respectively which resulted a 94% separation of apple from the tree in a shaking time of 10 seconds.

This study was carried out in Khouzestan province of Iran. Data were collected from 113 ratoon farms in Debel Khazai Agro-Industry with face to face questionnaire method. The objective of this study was to predict sugarcane production yield and GHG (greenhouse gas) emissions on the basis of energy inputs. Accordingly¡ several ANN (artificial neural network) models were developed and the prediction accuracy of them was evaluated using the quality parameters. The results illustrated that average total input and output energy of sugarcane production were 145117.7978 and 87096.42 MJ.ha-1¡ respectively. Electricity¡ chemical fertilizers and water for irrigation were the most influential factors in energy consumption. The ANN model with 6-7-19-1 and 5-5-1 structure were the best for predicting the sugarcane yield and GHG emissions¡ respectively. The coefficients of determination (R2) of the best topology were 0.96 and 0.99 for sugarcane yield and GHG emissions¡ respectively. The values of RMSE for sugarcane production and GHG emission were found to be 17763522 MJ.ha-1 and 528¡ respectively.

An important problem in harvesting walnuts is the case of harvesting machines for reducing the financial costs and labor injuries. Walnut harvesting is a costly and laborious practice in Iran¡ which causes significant costs and labor injuries each year. For resolving this problem¡ a simple and new machine designed and a prototype was fabricated. The mechanical range of operation of this machine is up to nine meters hight. It was simply operated by a motorcycle engine. This techniqe causes this equipment to be operational and practical in steep lands. With comparison to the traditional methods of walnuts harvesting¡ this machine improves safety and is easy to use¡ and there is no machine like this in Iran. It is worth mentioning that the capability and efficiency of the machine were tested and measured by different parameters such as speed and height. The results showed that there is a significant difference between the height levels (less than 2m¡ 2-3.5m¡ 3.5-5 m¡ 5-6.5 m) and also this machine is highly economical for the farmers as well as safe for the labors who are working in walnut trees. Based on results and investigations¡ this machine can be used to ease walnut harvesting in Iran.

Cuscuta Campestris L. is one of the alfalfa weeds. The best way to fight this weed is preventing field contamination and using Cuscuta free seeds. Now in many research centers¡ alfalfa seed infection percentage is manually calculated using of Binocular that requires high cost-time and has low accuracy. In this study¡ a computerized method was designed for calculating the percentage Cuscuta mixed with alfalfa seed. This method is based on image processing and application of artificial neural networks using a Matlab programming. Therefore¡ the desired images were obtained and then using a suitable threshold in Matlab programming¡ seeds were separated from the substrate surface. By using the geometrical relationship¡ dimensional characteristics of seeds were extracted. For both alfalfa seed and Cuscuta seed were used as inputs to the neural networks. To select the most suitable neural network topology¡ different types of networks with different transfer functions and learning functions and different numbers of neurons were examined and it was found that the topology 4-5-1whit Logsig transfer function and GDX learning function is able to detect the percentage of Cuscuta seed with a R2 of 0.956 and RMSE of 0.017.

In order to evaluate the effect of different amounts of nitrogen fertilizer¡ potassium¡ magnesium and zinc sulfate on the biodiesel production of sunflower and flax seeds oil¡ a field experiment was carried out in the research form of Shahrekord University in 2010. A factorial experiment was arranged in completely randomized block design with three replications. In the first treatment¡ two sunflower and flax and in the second treatment different levels of nitrogen at 150¡ 200 and 300 kg/ha¡ potassium¡ magnesium and zinc sulfate respectively at 150¡ 100 and 50 kg/ha and control were used. The biodiesel traits characteristics: heating value¡ cetane number¡ flash point and density were measured in both plants. The results showed that the convection and flash point¡ flax biodiesel have been lower than sunflower biodiesel¡ but the cetane number and density of biodiesel flax was found to be higher than biodiesel sunflower. Also¡ fertilizers application increased the density¡ heating value¡ flash point and cetane number. Potassium sulfate fertilizer shouled a stronger increasing effect as compared to the other fertilizers.

The first law of thermodynamics expresses the conservation of energy in all processes and does not apply any restriction on the transfer of energy. However¡ in recent years¡ in order to quantify the quality of energy¡ the concept of exergy has been defined widely used in design¡ simulation and evaluation of various thermal and thermochemical systems. In this study¡ the impact of the fuel and compression ratio on fuel chemical availabilities¡ thermomechanical and total availability in a spark ignition engine was examined. The results showed that by increasing the compression ratio¡ the shift process of the fuel chemical availability graph change. The parameter (a_th) at a compression ratio of 12 for the fuels E_0¡ E_20¡ E_40¡ E_60 and E_85increase to 9.2¡ 11¡ 10.9¡ 10.9 and 10.9% respectively¡ in comparison with compression ratio of 8. Also¡ total availability (a) at compression ratio of 12 is faster. exergy efficiency at compression ratio of 12 for fuels E_0¡ E_20 〖 ¡E〗_(40 )¡E_60 and E_85 increase to 11.7¡ 13.8¡ 11.3¡ 8.9 and 9.9% respectively¡ in comparison with compression ratio of 8%. It should be noted¡ that by increasing the amount of ethanol¡ terms exergy (thermo-mechanical¡ chemical fuel¡ and total) reduced. The efficiency of the second law of thermodynamics increased with increasing volume percent of ethanol.