Ergonomics of Farm Women in Manual Paddy Threshing

Abstract

Thin-layer drying experiments with Roselle (Hibiscus sabdariffa .L) were carried out in a constant temperature and humidity chamber. Four temperatures (35, 45, 55, and 65°C) and five relative humidities (30, 35, 40, 45, and 50%RH) were tested. Statistical analysis on twelve thinlayer drying model proved the superiority of two-term exponential model. The objectives of this work were to evaluate and validate the two-term exponential model; besides, examine the effects of the drying conditions on the drying rate and constant. Validation of the developed model was done using two criterions, plotting of the predicted against experimental moisture contents and the residual versus predicted moisture content. The average values of the drying constant (k) and coefficient (a) weA study was taken up to have a comparative study on the ergonomics of farm women in pedal threshing with single and double operators (N =15) and to suggest modifications for further reduction of human drudgery. The mean HR work was found to be 135.9 ± 1.3 and 121.2 ±1.0 beats/min respectively with single and double operators; a significant (P < 0.01) reduction of 10.82 %. The corresponding work pulse (Δ HR) was 65.7 ± 0.9 and 51.5 ± 1.6 beats/min. The Δ HR was more than the allowable limit of 40 beats/min. HR work steadied after 6 minutes of threshing and there was complete recovery of HR after 6 minutes with double operators and 8 minutes with single operator. The increase in HR/kg of grain threshed was found to be 146.4 ± 4.4 and 76.0 ± 4.1 in case of single and double operators respectively; a significant reduction of 48 %. The workload decreased by 13.5 % with double operators but was still higher than the allowable limit of 35 % of VO2 max. The energy expenditure rate (ERR) was 18.9 ± 0.4 kJ/min with single operator and reduced to 16.6 ± 0.3 kJ/min with double operators. The total cardiac cost of work (TCCW) and physiological cost of work (PCW) reduced by 19.84 and 20 % with double operators. No significant variation of blood lactate accumulation between single and double operators was observed. The pedal force required was 232.3 ± 7.0 N and 199.7 ± 5.8 N in case of single operator and double operators respectively but was higher than the mean leg strength of the women of the eastern region of India. Higher pedal force application with double operators increased the number strokes/min (96/min) leading to a 51.15 % increase in output capacity of the thresher per hour per person. An increase of length of the pedal by 2 cm was suggested to reduce the force requirement. The length of the threshing drum can be reduced from 60.5 cm to 40 cm to be used by single operator or it can be increased to 75 cm to comfortably accommodate two persons.e 0.009167 and 0.776132, respectively.