To examine the influence of the structural parameters and working parameters of a double-drum regeneration mixing station on its mixing uniformity,the influence of the discrete element method and response surface meth...To examine the influence of the structural parameters and working parameters of a double-drum regeneration mixing station on its mixing uniformity,the influence of the discrete element method and response surface method on the uniformity of the aggregate mixing when the interaction between two different factors was analyzed.A mathematical model of the influence of various factors and interactions on the coefficient of variation of the aggregates was established.The matching of each parameter was optimized with the goal of minimizing the coefficient of variation.The results show that when the aggregate particle size is different,the significance of each parameter affecting its mixing uniformity is also different.Moreover,increasing the speed and reducing the axial installation angle of the blade can reduce the coefficient of variation of the three aggregates.To obtain a good mixing uniformity,the mixing-arm phase angle when the drum inclination angle is large should be smaller than the phase angle when the drum inclination angle is small,and the mixing of large particles should not be arranged with a large mixing-arm phase angle.With a blade radial installation angle of 38°,a blade axial installation angle of 35°,a drum inclination angle of 6°,a drum rotation speed of 10 r/min,and a mixing-arm phase angle of 32°,the aggregate as a whole can exhibit the best mixing uniformity.展开更多
Rapid-cooling friction-stir-welding(FSW)was used to join AZ31B magnesium alloy plates of 6 mm in thickness.The microstructure and mechanical properties in thickness direction were carefully investigated with electron ...Rapid-cooling friction-stir-welding(FSW)was used to join AZ31B magnesium alloy plates of 6 mm in thickness.The microstructure and mechanical properties in thickness direction were carefully investigated with electron backscattered diffractometer,and transmission electron microscope.The obtained results showed that ultrafine grains with high dislocation density were obtained in the top region of the weld due to liquid CO2 cooling.A large number of{1012}twins and second-phase particles were also induced in these refined grains.The basal texture intensity was significantly reduced due to the appearance of{1012}twins.The top region showed the higher strength and elongation compared with the bottom region,and the welding efficiency reached 93%.This work provided a simple and efficient strategy for manufacturing a gradient structure in the FSW Mg alloy joint.展开更多
In this study,spent activated carbon(AC) saturated with caramel was regenerated by using yeast and NaOH.The efficiency of regeneration was evaluated under parameters such as amount,treatment time,temperature,pH value,...In this study,spent activated carbon(AC) saturated with caramel was regenerated by using yeast and NaOH.The efficiency of regeneration was evaluated under parameters such as amount,treatment time,temperature,pH value,stirring temperature of yeast and NaOH concentration.The optimum condition for AC regeneration was 8 h for yeast treatment time,35 ℃ for 0.075% yeast culture temperature,a pH value of 6 for the yeast dealing with the spent AC,90 ℃ for NaOH stirring temperature of AC and 6% NaOH for washing after the spent AC was treated by yeast.Under these conditions,methylene blue(MB) adsorption was 213 mg·g-1 in comparison with 60 mg·g-1 of spent AC.The micro structure and surface area of the regenerated AC were characterized by scanning electron mi-croscope(SEM) and N2 sorption,respectively.The pore size distributions of virgin and regenerated AC were ana-lyzed by means of H-K equation,resulting in a mean pore diameter of 1.28 nm and a pore volume of 1.13 cm3·g-1.This study provides data for theoretical support of the AC regeneration technology.展开更多
基金The Natural Science Basic Research Plan in Shaanxi Province(No.2017JM5077)the Fundamental Research Funds for the Central Universities under Grant(No.300102259109).
文摘To examine the influence of the structural parameters and working parameters of a double-drum regeneration mixing station on its mixing uniformity,the influence of the discrete element method and response surface method on the uniformity of the aggregate mixing when the interaction between two different factors was analyzed.A mathematical model of the influence of various factors and interactions on the coefficient of variation of the aggregates was established.The matching of each parameter was optimized with the goal of minimizing the coefficient of variation.The results show that when the aggregate particle size is different,the significance of each parameter affecting its mixing uniformity is also different.Moreover,increasing the speed and reducing the axial installation angle of the blade can reduce the coefficient of variation of the three aggregates.To obtain a good mixing uniformity,the mixing-arm phase angle when the drum inclination angle is large should be smaller than the phase angle when the drum inclination angle is small,and the mixing of large particles should not be arranged with a large mixing-arm phase angle.With a blade radial installation angle of 38°,a blade axial installation angle of 35°,a drum inclination angle of 6°,a drum rotation speed of 10 r/min,and a mixing-arm phase angle of 32°,the aggregate as a whole can exhibit the best mixing uniformity.
基金Project(51805145)supported by the National Natural Science Foundation of ChinaProject(CJ20200076)supported by the Changzhou Science and Technology Program,China+1 种基金Project(B200202229)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(2020102941517)supported by Hohai University Undergraduate Innovation and Entrepreneurship Training Program,China。
文摘Rapid-cooling friction-stir-welding(FSW)was used to join AZ31B magnesium alloy plates of 6 mm in thickness.The microstructure and mechanical properties in thickness direction were carefully investigated with electron backscattered diffractometer,and transmission electron microscope.The obtained results showed that ultrafine grains with high dislocation density were obtained in the top region of the weld due to liquid CO2 cooling.A large number of{1012}twins and second-phase particles were also induced in these refined grains.The basal texture intensity was significantly reduced due to the appearance of{1012}twins.The top region showed the higher strength and elongation compared with the bottom region,and the welding efficiency reached 93%.This work provided a simple and efficient strategy for manufacturing a gradient structure in the FSW Mg alloy joint.
基金Supported by the Fundamental Research Funds for the Central Universities (2011YXL056)National Program of Controland Treatment of Water Pollution (2009ZX07424-002)
文摘In this study,spent activated carbon(AC) saturated with caramel was regenerated by using yeast and NaOH.The efficiency of regeneration was evaluated under parameters such as amount,treatment time,temperature,pH value,stirring temperature of yeast and NaOH concentration.The optimum condition for AC regeneration was 8 h for yeast treatment time,35 ℃ for 0.075% yeast culture temperature,a pH value of 6 for the yeast dealing with the spent AC,90 ℃ for NaOH stirring temperature of AC and 6% NaOH for washing after the spent AC was treated by yeast.Under these conditions,methylene blue(MB) adsorption was 213 mg·g-1 in comparison with 60 mg·g-1 of spent AC.The micro structure and surface area of the regenerated AC were characterized by scanning electron mi-croscope(SEM) and N2 sorption,respectively.The pore size distributions of virgin and regenerated AC were ana-lyzed by means of H-K equation,resulting in a mean pore diameter of 1.28 nm and a pore volume of 1.13 cm3·g-1.This study provides data for theoretical support of the AC regeneration technology.
