In this paper, particle image velocimetry (PIV) was used to measure the mean and root meansquare(RMS) velocity in the stirred tank with six-flat blade Rushton turbine and with no baffles. Two typesof motion patterns w...In this paper, particle image velocimetry (PIV) was used to measure the mean and root meansquare(RMS) velocity in the stirred tank with six-flat blade Rushton turbine and with no baffles. Two typesof motion patterns were studied. One was that the impeller runs at constant speed, the other was that the impellerruns at time-dependent speed and in a periodic way. The emphasis of the paper was on the comparison of meanand RMS velocity vector maps and profiles between these two types of motion patterns, and especial attention waspaid to the comparison of the mean velocity, time-averaged RMS velocity, phase averaged RMS velocity betweenthe constant 3 RPS (revolution per second) and time-dependent operation. The Reynolds number was between 763and 1527. The study explained the mechanism that time-dependent RPS is more efficient for mixing than that ofconstant RPS.展开更多
Two types of the dual mode-locked fiber lasers for asynchronous absolute distance measurement are investigated, The lasers are linear and ring cavity with repetition rate of 70 MHz and 100 MHz, respectively. The group...Two types of the dual mode-locked fiber lasers for asynchronous absolute distance measurement are investigated, The lasers are linear and ring cavity with repetition rate of 70 MHz and 100 MHz, respectively. The group velocity dispersion is not compensated in the first type of the lasers, while the others are fully done. The timing jitter with the Allan deviation below averaging time of 0.2 s during the distance measurement for around 1 m of both types of lasers were 2.5 ps with 600 nm and 1.6 ps with 200 nm. We concluded that the phase noise resulted from the intra-cavity dispersion is the main contribution for the uncertainty of the ranging in these two types of the lasers.展开更多
文摘In this paper, particle image velocimetry (PIV) was used to measure the mean and root meansquare(RMS) velocity in the stirred tank with six-flat blade Rushton turbine and with no baffles. Two typesof motion patterns were studied. One was that the impeller runs at constant speed, the other was that the impellerruns at time-dependent speed and in a periodic way. The emphasis of the paper was on the comparison of meanand RMS velocity vector maps and profiles between these two types of motion patterns, and especial attention waspaid to the comparison of the mean velocity, time-averaged RMS velocity, phase averaged RMS velocity betweenthe constant 3 RPS (revolution per second) and time-dependent operation. The Reynolds number was between 763and 1527. The study explained the mechanism that time-dependent RPS is more efficient for mixing than that ofconstant RPS.
文摘Two types of the dual mode-locked fiber lasers for asynchronous absolute distance measurement are investigated, The lasers are linear and ring cavity with repetition rate of 70 MHz and 100 MHz, respectively. The group velocity dispersion is not compensated in the first type of the lasers, while the others are fully done. The timing jitter with the Allan deviation below averaging time of 0.2 s during the distance measurement for around 1 m of both types of lasers were 2.5 ps with 600 nm and 1.6 ps with 200 nm. We concluded that the phase noise resulted from the intra-cavity dispersion is the main contribution for the uncertainty of the ranging in these two types of the lasers.
