مجله پژوهش های مکانیک ماشین های کشاورزی
سال سوم شماره 2 (پاییز و زمستان 1393)

Wheat is one of the most important and strategica crops in Iran and the world. It is rich in protein and has a high economic value. Therefore, it is very important to determine the safety of wheat. The objective of this study was to identify wheat kernels infected by fungi, such as Penicillium Expansum and Fusarium Graminearum using setup of monochromator and imaging in visible and non-visible range. Alvand and Sardari wheat cultivars that allocated more cultivation area in the country were chosen for this purpose and three following comprehensive systems were used. The basis of the first system was employing detector and imaging visibly and non-visibly in the range of 630-680 nm of laser light. Setup of monochromator and image analysis in the visible and non-visible ranges were used in second and third system, respectively. For this purpose, CCD visible camera, visible-infrared and infrared cameras used for imaging of healthy and unhealthy wheat samples in ultraviolet, visible and infrared lights. In this system, eighteen features in RGB, LAB, HSV, HSI, YCbCr, and YIQ color spaces were extracted and used as neural network inputs. Wheat samples are classified into six classes of healthy Sardari, healthy Alvand, Sardari infected with Fusarium, Sardari infected with Penicillium, Alvand infected with Fusarium and Alvand infected with Penicillium.

Farm information management systems provide proper decisions by collecting precise locative data of the farm in a non-destructive and immediate form at any time. Nowadays, laser is used in a wide range of industries such as target equipment’s and exact instruments. The research was designed and performed and evaluated to identify and measure crop plants height in a non-destructive form using the laser technology. After designing and building, the laser system was tested in two field and laboratorial stages. The first stage of measurement was performed on the rice in a laboratorial environment which the collected data were analyzed by linear regression method (repression coefficient %95) and average comparison after calibration that represented sufficient care of the system in identifying the product height. In the second stage, it was used the laser system to measure the wheat height on the farm which according to the obtained results, it wasnt observed significant statistical difference between the height data measured in meter and the system data. According to the obtained results, the laser sensor system is recommended as a suitable and with high precision method for kinds of product locative identification operations and identifying the height of various products in precise agriculture.

Seed spacing uniformity is an important criterion in evaluating seeder performance; so that, it is affected by the vacuum pressure value of the pneumatic seeder, proportional to seed weight and size, the physical properties of the seeds, the forward speed, quality of seed, and seed fall speed. Therefore, in this study, the effects of two levels of actual forward speed and three levels of vacuum pressure for maize and castor seeds were evaluated to determine seed falling speed using free fall equations (first method) and seed displacement during consecutive frames by image processing (second method) The acceleration values obtained for two mentioned methods were equal to 9.47 m.s-2 and 15.75 m.s-2, respectively. To confirm accuracy of the values obtained, locations of seeds were calculated using the equation of -time-position for the both methods and it was compared to the obtained values of image processing. According to the correlation coefficient of 0.89 and 0.99, and root mean square error of 3/09×10-2 and 1/22×10-2, for the first and second method, respectively, the second method shows better results than the first method.

In recent years, the attention to human factors engineering has been increased in industrial transportation due to its importance to the health and safety of drivers. Since tractors are very important machines in agricultural operations, therefore the ergonomics of these machines should be taken into consideration. Accordingly an ergonomics seat cushion for Iranians operators was designed to reduce vibrations transmitted to tractors operator's body in order to improve driver comfort level. The designed air seat cushion model was compared with existing seat cushion. Both seat cushion models were analyzed using the finite element method in the frequency range of 3 to 66 Hz for three drivers with masses of 55, 70 and 85 kg. The results of this study showed that designed air seat mattress reduced accelerations output in range if driver comfort level, while the results of seat backrest acceleration outputs, show more comfort levels in existing seats backrest model. Therefore, by combining the existing seat back rest and designed air seat mattress make a better seat design and can provide more comfort and convenience level for Iranian tractor drivers.

In this research a stirred digester with curved full blade turbine was designed and analyzed using mathematical equations and ABACUS software according to needed biogas / methane for a village with 1000 persons. The results of designing showed that mixer diameter, digester diameter and shaft length were 1.38, 3, and 2.385 m, respectively, steel density existing in mixer structure was 8000 kg/m3, liquid density was 1000 kg/m3 and rotational speed was 0.25 rev/s. The engine power and torque was 0.39 kw and 250 Nm, respectively with confidence coefficient of 1.5. Its vanes included blade and T shape arm, which corresponding dimensions were 4×276×320 and 20+320) ×90×18 mm, respectively. Equivalent force from liquid on the blade was 78 N and its moment was 46 N-m. Equivalent bending moment on shaft calculated using Van Maize law was 1414.3 Nm. The shaft diameter calculated by true and error method was 60 mm. A 3 dimensional design of mixer was drawn by CATIA software according to calculated parameters in this research and it was analyzing by ABACUS software. The software results showed that however the stress in T shape arms was higher than the other parts of mixer, but it was lower than critical selected stress for mixer. Furthermore the stress in the other parts of mixer was very low. Therefore the mixer with these parameters can truly work in digester with no problem.

Bean is cultivated in conventional and semi mechanized methods. Information about this research such as fuel consumption and agricultural operation time spent for planting and harvesting steps in conventional and semi mechanized cultivation system were collected by face to face and questionnaire methods as well as samples (30) were collected by randomized selection. The results showed that the amount of total input energy for conventional and mechanized methods were equal to 66556. 16 and 89181. 30 MJ/ha، respectively. Chemical fertilizer was the most commonly used input in both of cultivation systems followed by electrical and fuel consumption in conventional system and fuel consumption and chemical pesticides in semi mechanized system. The energy efficiency was equal to 0. 66 and 0. 41 for the conventional and semi mechanized methods، respectively.