Recently impregnated diamond bits have been widely applied in drilling hard and medium - hard formations in the world . It is quite necessary to study the fracturing mecha-nism of the impregnated diamond bit and the c...Recently impregnated diamond bits have been widely applied in drilling hard and medium - hard formations in the world . It is quite necessary to study the fracturing mecha-nism of the impregnated diamond bit and the classification of rocks , which can realize optimum drilling . Using multi - parameter rotary test stand can monitor and print nine parameters . The diamond size and concentration for experiment are various and there are nearly 200 types of samples , numbering over 1000 pieces . The results of laboratory are the same as those in the field . Besides , this paper expresses that the diamond concentration of impregnated diamond bits effect the bonding strength of diamond imbedded in ma-trix . During drilling by impregnated diamond bits three ways are used to cool the bits . The contact area between impregnated diamond layer and flow , and the drilling flow through annulus carrying away heat with conduction form can be shown by equations . It is impossible to classify the rock drillability only by using single factor . The best method is to use main factors to analyse the drillability of rocks. Only in this way , the results can be applied to practice .展开更多
Maize shelling activity by the small scale farmers is done manually by either stripping with fingers,beating bagged cops with sticks or rubbing two cobs against each other.Shelling forms part of maize post-harvest los...Maize shelling activity by the small scale farmers is done manually by either stripping with fingers,beating bagged cops with sticks or rubbing two cobs against each other.Shelling forms part of maize post-harvest losses which span from harvesting to consumption.The objective of this research was to demonstrate,test and evaluate the maize shellers in Meru County.The scope applied to one diesel(control)and three locally fabricated gasoline-powered throw-in type maize shellers and was performed on-farm at three different commercial villages(CVs).Traditional methods of shelling were compared to motorized shellers followed by the comparison between the 8 horsepower(hp)diesel(control)and 5 hp locally fabricated gasoline-powered shellers.The average shelling capacity(1,384 kg/h)and shelling efficiency(97.8%)of the locally fabricated shellers were lower as compared to the control(2,138 kg/h)with a shelling efficiency of 99.93%.The average scattering losses for the locally fabricated shellers were high(12.6%)compared to the control(0.053%).The analysis of variance(ANOVA)revealed control had the highest mean(9.23)and p value>0.05 hence more efficient compared to locally fabricated(9.15).The shellers lacked the cleaning component,hence shelled maize required cleaning by winnowing manually and were not gender friendly since women and people enabled differently(PED)could not operate the machine due to height of the feeding hopper compared to control.It took traditional methods longer(59.4 s)to perform a shelling operation compared to using motorized shellers(15 s).The efficient control sheller demonstrated reduced farmers’drudgery and post-harvest losses and was recommended for use by the small scale farmers in the county.展开更多
文摘Recently impregnated diamond bits have been widely applied in drilling hard and medium - hard formations in the world . It is quite necessary to study the fracturing mecha-nism of the impregnated diamond bit and the classification of rocks , which can realize optimum drilling . Using multi - parameter rotary test stand can monitor and print nine parameters . The diamond size and concentration for experiment are various and there are nearly 200 types of samples , numbering over 1000 pieces . The results of laboratory are the same as those in the field . Besides , this paper expresses that the diamond concentration of impregnated diamond bits effect the bonding strength of diamond imbedded in ma-trix . During drilling by impregnated diamond bits three ways are used to cool the bits . The contact area between impregnated diamond layer and flow , and the drilling flow through annulus carrying away heat with conduction form can be shown by equations . It is impossible to classify the rock drillability only by using single factor . The best method is to use main factors to analyse the drillability of rocks. Only in this way , the results can be applied to practice .
文摘Maize shelling activity by the small scale farmers is done manually by either stripping with fingers,beating bagged cops with sticks or rubbing two cobs against each other.Shelling forms part of maize post-harvest losses which span from harvesting to consumption.The objective of this research was to demonstrate,test and evaluate the maize shellers in Meru County.The scope applied to one diesel(control)and three locally fabricated gasoline-powered throw-in type maize shellers and was performed on-farm at three different commercial villages(CVs).Traditional methods of shelling were compared to motorized shellers followed by the comparison between the 8 horsepower(hp)diesel(control)and 5 hp locally fabricated gasoline-powered shellers.The average shelling capacity(1,384 kg/h)and shelling efficiency(97.8%)of the locally fabricated shellers were lower as compared to the control(2,138 kg/h)with a shelling efficiency of 99.93%.The average scattering losses for the locally fabricated shellers were high(12.6%)compared to the control(0.053%).The analysis of variance(ANOVA)revealed control had the highest mean(9.23)and p value>0.05 hence more efficient compared to locally fabricated(9.15).The shellers lacked the cleaning component,hence shelled maize required cleaning by winnowing manually and were not gender friendly since women and people enabled differently(PED)could not operate the machine due to height of the feeding hopper compared to control.It took traditional methods longer(59.4 s)to perform a shelling operation compared to using motorized shellers(15 s).The efficient control sheller demonstrated reduced farmers’drudgery and post-harvest losses and was recommended for use by the small scale farmers in the county.
