A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted....A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted. The tests show that the ignitor and the main charge of the microthruster match well, the dynamic and static capability of the test and measurement meets the test requirement and the result is creditable. The measured technical characteristics of the microthruster are that the ignition delay time is shorter than 0 3?ms, the total impulse is over 3?N·s, the operational time is shorter than 16?ms and the mass ratio of the thruster is 0 216.展开更多
This study was performed to investigate the feasibility of applying a Rotary Triboelectrostatic Separator（RTS） to the beneficiation of Eshidiya phosphate minerals.RTS separation tests were carried out on phosphatic ...This study was performed to investigate the feasibility of applying a Rotary Triboelectrostatic Separator（RTS） to the beneficiation of Eshidiya phosphate minerals.RTS separation tests were carried out on phosphatic bed A_1,phosphatic bed A_3 and slime samples.The bed A_1 and slime samples were tested without desliming.Two sets of tests were performed using the A_3 sample： one was performed without desliming and the other with the A_3 sample deslimed.RTS separation tests as initially performed on the bed A_1 and slime samples gave products that had essentially the same P_2O_5 content.This indicated that adsorbed clay particles on the phosphate surface are responsible for the poor separation of un-deslimed phosphates.Better triboelectrostatic separation was observed with the undeslimed A_3 phosphate sample;these tests resulted in a highest product grade of 26%P_2O_5.The deslimed A_3 sample showed far more effective separation than the undeslimed A_3 one.In fact,a concentrate of 34%P_2O_5 was obtained from the triboelectrcstatic separation of deslimed A_3.The results indicate that with deslimed A_3 P_2O_5 recovery was about 65%for a concentrate of 28%P_2O_5 and about 45%for a concentrate of 30%P_2O_5.These results clearly show the importance of desliming for effective beneficiation of phosphate by the RTS.A more efficient separation can be expected from optimized operating conditions and circuit configuration.展开更多
Based on laboratory results of time-dependent mechanical behavior tests,we investigated short-term and mechanical creep behavior of sandstone,observed in conventional triaxial compression experiments at room temperatu...Based on laboratory results of time-dependent mechanical behavior tests,we investigated short-term and mechanical creep behavior of sandstone,observed in conventional triaxial compression experiments at room temperature,using a servo-controlled rheology testing machine.Given our short-term experimental test results,we confirmed deviatoric creep stress levels of sandstone.Multiple deviatoric stress levels were applied in steps to each sample.Each deviatoric stress level before the final failed deviatoric stress was maintained for 48 h or longer.Time-dependent variations of axial strains of sandstone samples are discussed and evaluated.During the creep tests,complete tertiary creep curves of sandstone were observed under failed deviatoric stress levels with different confining pressures.Slices of coal in sandstone samples can lead to distinct tertiary creep deformation failure.展开更多
文摘A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted. The tests show that the ignitor and the main charge of the microthruster match well, the dynamic and static capability of the test and measurement meets the test requirement and the result is creditable. The measured technical characteristics of the microthruster are that the ignition delay time is shorter than 0 3?ms, the total impulse is over 3?N·s, the operational time is shorter than 16?ms and the mass ratio of the thruster is 0 216.
基金the staff of the Jordan Phosphate Mines Company for supplying the sample used in the present work.
文摘This study was performed to investigate the feasibility of applying a Rotary Triboelectrostatic Separator（RTS） to the beneficiation of Eshidiya phosphate minerals.RTS separation tests were carried out on phosphatic bed A_1,phosphatic bed A_3 and slime samples.The bed A_1 and slime samples were tested without desliming.Two sets of tests were performed using the A_3 sample： one was performed without desliming and the other with the A_3 sample deslimed.RTS separation tests as initially performed on the bed A_1 and slime samples gave products that had essentially the same P_2O_5 content.This indicated that adsorbed clay particles on the phosphate surface are responsible for the poor separation of un-deslimed phosphates.Better triboelectrostatic separation was observed with the undeslimed A_3 phosphate sample;these tests resulted in a highest product grade of 26%P_2O_5.The deslimed A_3 sample showed far more effective separation than the undeslimed A_3 one.In fact,a concentrate of 34%P_2O_5 was obtained from the triboelectrcstatic separation of deslimed A_3.The results indicate that with deslimed A_3 P_2O_5 recovery was about 65%for a concentrate of 28%P_2O_5 and about 45%for a concentrate of 30%P_2O_5.These results clearly show the importance of desliming for effective beneficiation of phosphate by the RTS.A more efficient separation can be expected from optimized operating conditions and circuit configuration.
基金Projects 50709008 and 50539110 are supported by the National Natural Science Foundation of China.
文摘Based on laboratory results of time-dependent mechanical behavior tests,we investigated short-term and mechanical creep behavior of sandstone,observed in conventional triaxial compression experiments at room temperature,using a servo-controlled rheology testing machine.Given our short-term experimental test results,we confirmed deviatoric creep stress levels of sandstone.Multiple deviatoric stress levels were applied in steps to each sample.Each deviatoric stress level before the final failed deviatoric stress was maintained for 48 h or longer.Time-dependent variations of axial strains of sandstone samples are discussed and evaluated.During the creep tests,complete tertiary creep curves of sandstone were observed under failed deviatoric stress levels with different confining pressures.Slices of coal in sandstone samples can lead to distinct tertiary creep deformation failure.
