جستجوی مقالات مرتبط با کلیدواژه « frequency analysis » در نشریات گروه « مکانیزاسیون کشاورزی »

Hearing loss due to harmful sound is one of the most important occupational illnesses. Agricultural mechanization with the use of a variety of machinery causes problems in occupational safety and health for those working in this field. In this study, some of the factors affecting the noise generated by a garden tractor (H.938 Model) were evaluated and predicted. The tests were performed according to international standards of sound such as ISO 5131 and ISO 7216 at different engine speeds, gear positions, road type and microphone distance. The total number of treatment combinations for extracting sound signals released by the garden tractor reached 216 with 72 treatments and three repetitions. The obtained data were analyzed in the form of a factorial test based on a completely random plan. Besides, Artificial Neural Network and ANFIS model was created to predict the sound level in the aforementioned tractor with 216 patterns for training and assessment. The results of the research showed that the effect of the main factors on the level of sound emitted by the garden tractor were significant at probability level of 1%. The results of frequency analysis showed that noise pressure level decreases according to increase in frequency and the sound intensity that reaches the driver's ear is equal to 77.93 dB at the frequency of 4000 Hz. The results of Artificial Neural Network and ANFIS model for forecasting the Sound pressure level of the garden tractor with the highest coefficient of determination (R2) for this research were 99.73 and 99.91, respectively.

Workplace factors such as sound must have the minimum impact on the operators of combine harvester، so that they can guide and control many functions of the combine. In this study، some factors affecting the noise generated by two combine harvesters John Deere 1055 and Sampo 3065 were evaluated. Research factors were engine speed، gear ratios، type of operation and microphone distance. The results of this study indicated that sound pressure level decreased with increasing center frequencies. The sound pressure level of John Deere and Sampo combine at center frequency of 4000 Hz were 87. 96 and 84. 73 db، respectively. The results showed also that the maximum sound pressure of John Deere and Sampo combines were116db at frequency of 250 Hz and 111. 1db at frequency of 40 Hz، respectively.