Fluid flow in the microchannel is limited to the low Reynolds number regime.As a result,mixing of solutions with different concentrations in the microchannel is inherently diffusion dominated,requiring a long mixing c...Fluid flow in the microchannel is limited to the low Reynolds number regime.As a result,mixing of solutions with different concentrations in the microchannel is inherently diffusion dominated,requiring a long mixing channel and retention time to attain a homogeneous solution.In this paper the flow characteristics in the two-dimension closed-end microchannel electroosmotic flow were simulated,and the mixing efficiencies of the closed-end microchannel electroosmotic flow applying different electric field intensities were compared.The results showed that because of existing non-uniform induced back pressure,there were two annular flows in the whole closed-end microchannel,enhancing the convection effect and leading to a shorter mixing time and higher mixing efficiency.展开更多
A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pul...A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pulse width control (PWM) method. Compared with the conventional phase-controlled dimmer, the proposed PWM dimmer can produce sine wave and did not cause harmonics problem. Furthermore, the proposed control method did not amplify the light flicker due to the independence of input voltage. Therefore, the PWM dimmer can be used as the dimmer of the AC LED lamp instead of the conventional phase-controlled dimmer. The experimental result shows that the proposed PWM dimmer has good performances.展开更多
文摘Fluid flow in the microchannel is limited to the low Reynolds number regime.As a result,mixing of solutions with different concentrations in the microchannel is inherently diffusion dominated,requiring a long mixing channel and retention time to attain a homogeneous solution.In this paper the flow characteristics in the two-dimension closed-end microchannel electroosmotic flow were simulated,and the mixing efficiencies of the closed-end microchannel electroosmotic flow applying different electric field intensities were compared.The results showed that because of existing non-uniform induced back pressure,there were two annular flows in the whole closed-end microchannel,enhancing the convection effect and leading to a shorter mixing time and higher mixing efficiency.
文摘A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pulse width control (PWM) method. Compared with the conventional phase-controlled dimmer, the proposed PWM dimmer can produce sine wave and did not cause harmonics problem. Furthermore, the proposed control method did not amplify the light flicker due to the independence of input voltage. Therefore, the PWM dimmer can be used as the dimmer of the AC LED lamp instead of the conventional phase-controlled dimmer. The experimental result shows that the proposed PWM dimmer has good performances.
