Three drums with different helical angles （15°, 20°, and 25°） were developed to investigate improved loading performance of the shearer drum. Nine trials were performed at different drum rotation spee...Three drums with different helical angles （15°, 20°, and 25°） were developed to investigate improved loading performance of the shearer drum. Nine trials were performed at different drum rotation speeds （80, 100, and 120 r/min） and different haulage speeds （1.5, 2.0, and 2.5 m/min） in an orthogonal test design. Loaded coal quantity and cutting power of the drum were the responses measured under the dif- ferent conditions. The effect of the parameters was determined by means of the extreme difference method. The significance of the effects was determined by analysis of variance. The results indicate that the effect from changes in the helical vane on loading performance of the drum is the largest in magnitude. The haulage speed has the least affect on loading performance. The helical angle has the least affect on cutting power of the drum. Haulage speed has the largest affect on the cutting power of the drum. 2011 Published by Elsevier B.V. on behalf of China University of Mining ＆ Technology.展开更多
In Africa, donkeys have significant contribution in traction operation, but there is little research related to workload and their welfare. The objective of this work was to examine the effect of various loads on donk...In Africa, donkeys have significant contribution in traction operation, but there is little research related to workload and their welfare. The objective of this work was to examine the effect of various loads on donkeys＇ physiological and behavioural responses to evaluate welfare. Donkeys weighing of 132-172 kg （159 ± 11 kg） and totally 20 were used for the experiment. The experimental design included two wheeled cart × seven load class （an increment of 100 kg） with five repetitions each, and the travelled distance was 2 km. Travelled time, behavioural occurrences and physiological responses were recorded. Statistical analysis was conducted using SAS （version 9.4） software programme. When loads were 500-700 kg, heavy and rapid panting and falling down occurred frequently. When loads increased successively and reached 500, 600 and 700 kg, speed started declining from 3.68 km/hto 3.5, 2.94 and 2.54 krn/h, respectively, indicating that speed and applied loads are inversely correlated （P 〈 0.001）. Heart rate was 129 ± 11 bpm at 700 kg, and in respect to resting state, donkeys＇ heart rate elevated by a factor of up to 3. As the load exceeded 400 kg, the speed declined significantly, and behavioural occurrences like heavy panting and falling down confirmed this. This leads to the conclusion that donkeys could pull about 2.7 times of their live weight. But if they have continuous and long working hours （about 6 h）, it is recommended to keep load of two wheeled cart about double of donkeys live weight so as to safe guard donkeys＇ welfare.展开更多
基金support for this work was provided by the National Natural Science Foundation of China (No. 51005232)the China Postdoctoral Science Foundation (No. 20100481176)
文摘Three drums with different helical angles （15°, 20°, and 25°） were developed to investigate improved loading performance of the shearer drum. Nine trials were performed at different drum rotation speeds （80, 100, and 120 r/min） and different haulage speeds （1.5, 2.0, and 2.5 m/min） in an orthogonal test design. Loaded coal quantity and cutting power of the drum were the responses measured under the dif- ferent conditions. The effect of the parameters was determined by means of the extreme difference method. The significance of the effects was determined by analysis of variance. The results indicate that the effect from changes in the helical vane on loading performance of the drum is the largest in magnitude. The haulage speed has the least affect on loading performance. The helical angle has the least affect on cutting power of the drum. Haulage speed has the largest affect on the cutting power of the drum. 2011 Published by Elsevier B.V. on behalf of China University of Mining ＆ Technology.
文摘In Africa, donkeys have significant contribution in traction operation, but there is little research related to workload and their welfare. The objective of this work was to examine the effect of various loads on donkeys＇ physiological and behavioural responses to evaluate welfare. Donkeys weighing of 132-172 kg （159 ± 11 kg） and totally 20 were used for the experiment. The experimental design included two wheeled cart × seven load class （an increment of 100 kg） with five repetitions each, and the travelled distance was 2 km. Travelled time, behavioural occurrences and physiological responses were recorded. Statistical analysis was conducted using SAS （version 9.4） software programme. When loads were 500-700 kg, heavy and rapid panting and falling down occurred frequently. When loads increased successively and reached 500, 600 and 700 kg, speed started declining from 3.68 km/hto 3.5, 2.94 and 2.54 krn/h, respectively, indicating that speed and applied loads are inversely correlated （P 〈 0.001）. Heart rate was 129 ± 11 bpm at 700 kg, and in respect to resting state, donkeys＇ heart rate elevated by a factor of up to 3. As the load exceeded 400 kg, the speed declined significantly, and behavioural occurrences like heavy panting and falling down confirmed this. This leads to the conclusion that donkeys could pull about 2.7 times of their live weight. But if they have continuous and long working hours （about 6 h）, it is recommended to keep load of two wheeled cart about double of donkeys live weight so as to safe guard donkeys＇ welfare.
