Journal of Researches in Mechanics of Agricultural Machinery

Abstract One of the most important issues in the management of production is how to select the best option for each production activity, so that the time and cost of production are minimized and the quality is simultaneously maximized. Considering a large number of activities and possible options for them, this choice does not have a unique solution and can be used the utility function and assign weights to time, cost and quality in order to select the best answer from those obtained. Since in reality a vast amount of uncertainty can be observed, an effective management necessitates dealing with these uncertainty issues. In this study, a fuzzy math model for a chain of activities is suggested to determine the best practical method employed by the milk production process. In order to achieve this goal, fuzzy alpha cut was employed to manage the risk of these series of activities. Accordingly, Non-dominated Sorting Genetic Algorithm-II (NSGA-II) with fuzzy inputs was used and the best method of implementation for each activity of milk production process from the starting point of cows birth to the ending point of removing these cows from the herd was introduced.

Abstract This research was aimed at finding the most suitable solar energy absorption system for use in greenhouses. For this purpose, 5five greenhouses were built in Izeh township and each one with area of 10m2. Five separate systems were implemented including common system,, solar water heater, water wall, stone bed and phase-change material. The research was conducted during six months. Technical factors including functional safety, useful life, reliability, ease of maintenance and repairs together with economical and environmental factors were investigated and compared by Duncan’s test and finally, the method of Analytic Hierarchy process (AHP) was used to introduce the best system. The result showed that the solar water heater system has higher cost and energy absorption also lower average time to repair and phase-change material method has the least failure frequency. The analytic hierarchy process (AHP) revealed the water wall as the most appropriate system and then the solar water heater. Although solar water heater consumes less fuel but it has more cost, lower sale services, failure frequency and it has repeating accident rate more than water wall. This method can be in the first place by reducing cost and improving after – sale services. Placing the traditional method in the last rank, shows that it was not suitable and its use should be reassessed.

Abstract the rotation speed from ??rpm to ???rpm, the amounts of CH? and CO within the biogas The goal of the present study was to study the effect of mixer speed on biogas compounds produced from semi-industrial biogas plant. The biogas was produced with slurry made by combination of ??% cow manure, ??% municipal waste and ?% kitchen waste with adding ?.??% NaOH and ?.??% H?O? as the chemical pretreatment. Then, the effect of mixer rotation speed on mixing quality of the slurry was linked to the anaerobic microbial communities and some of physical and chemical parameters of the slurry. The results showed that by increasing compound increased by ?.?% and ??.?%, and the amounts of H?S and O? decreased by ?% and ?.?%, respectively. This observation was due to decrease in the chemical oxygen demand (COD) and total volatile solids (TVS) of the slurry by ?.?% and ?.?%, respectively because of an increase in the anaerobic microbial communities by ?.?%. Furthermore, the same trend existed between the CH? and anaerobic microbial communities of the slurry that was similar to the COD and TVS decreasing trends.

Abstract This study was aimed to investigate the effect of the differential lock on the drive wheel slip and fuel consumption rates for the three tractors (ITM??? ?WD-ITM??? ?WD-ITM??? ?WD). In this research, the factors were tillage depth at two levels (?? and ?? cm) and differential lock (engaged and not engaged). The experiments were carried out based on factorial experiment in randomized complete block design with three replications separately for each tractor. The experiments were conducted in the same conditions with appropriate soil sitaution at the research field of Shahrekord University. Analysis of factors effects were obtained by measuring the parameters of drive wheels slip, fuel consumption of the tractor and the travelling time. The results showed that the use of differential lock during moldboard plow for all tractors caused to reduce the fuel consumption and the route travel time. The use of differential lock had significant effect on the driving wheel slip of tractor, in such a way by using of differential lock, the average of rear right wheel slip and the rear left wheel slip reduced as ??.?? %and ??.?? respectively. Also, with increasing in plowing depth the driving wheels slip, fuel consumption and the rout travel for all tractors increased in two situations of differential lock.

Abstract In order to prevent major problems in terms of occupational health and safety for tractor drivers, identification of vibration sources as well as limitation of their amplitude are necessary. In this study, a number of factors affecting on the Seat Effective Amplitude Transmissibility (SEAT) of three tractors, Goldoni 341, Massey Ferguson 285 and John Deere 3140, were evaluated. The factors were type of route, gear ratios and engine speed. Accordingly, a factorial experiment based on randomized complete block was designed with three replications. The results of this study showed that the levels of type of route, gear ratio and engine speed for all three tractors were significant at the 1% level. However, the changes in engine speed related to gear ratio showed a more even trend in SEAT. The tractors showed different behaviors on the types of route, so that the plowed route in Goldoni and John Deere tractors had the highest value of SEAT in comparison with other routes (paved roads and rural roads). However, the opposite trend was observed in Massey Ferguson. The maximum and minimum range of SEAT with 98.2 and 22.6% for Goldoni and John Deere tractors were achieved, respectively.

Abstract Qualitative grading and classifying of rice are one of the factors affecting on the marketing and customer satisfaction. The objective of this study was to develop an accurate algorithm for characterization of three important qualitative indices of rice including percentage of broken grains, percentage of chalky grains and degree of milling. Some rice samples of a variety namely 'AliKazemi' were provided from Rice Research Institute of Iran. After questioning expert persons, three quantitative levels (Low, Medium and High) were defined. The images of each of the 270 samples of rice grains were captured under the same conditions. In development of fuzzy inference model for the product pricing, the Mamdani inference system was applied and defuzzification process was done using Center of Area defuzzifier. Results indicated that the average accuracy of the image processing algorithm in detecting percentage of broken grains, percentage of chalky grains and degree of milling was respectively as 95.2%, 90.74% and 98.99%. The decisions made by the fuzzy model were consistent with the expert’s judgment in 95.2% of the cases. This system can be good alternative to traditional methods used in market and rice processing factory to characterize the rice key propertiesfast and more accurately