Browsing by Author "Lo, H. P."

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Controllable subwavelength-ripple and -dot structures on YBa2Cu3O7 induced by ultrashort laser pulses
(2012-11-01)
Luo, C. W.
;
Tang, W. T.
;
Wang, H. I.
;
Liao, L. W.
;
Lo, H. P.
The evolution of periodic ripples and dots on an YBa2Cu3O7 surface irradiated by single-beam and dual-beam femtosecond laser pulses is investigated. The density and size of the dots can be controlled by the number of pulses. The spatial period of these ripples does not show a close relation to the pulse number. However, the orientation and geometrical period of the ripples are strongly dependent on the polarization and incident angle of the laser pulses, respectively. The formation processes are also discussed based on the dependence.
Doping dependence of the ultrafast electronic dynamics of Y(1-x)Pr(x)Ba(2)Cu(3)O(7-delta) thin-film superconductors from femtosecond optical spectroscopy
(2010-09-17)
Luo, C. W.
;
Lo, H. P.
;
Su, C. H.
;
Wu, I. H.
;
Chen, Y. -J.
Time-domain spectroscopy, which probes the dynamics of the electronic states near Fermi surface that are associated with superconductivity, has proven to be a powerful method for providing insights into the fundamental nature of both pseudogap and superconducting gap. This study shows that the unique T-x phase diagram with the time-evolving ultrafast dynamics of Y(1-x)Pr(x)Ba(2)Cu(3)O(7-delta) can be used to identify clearly the Nernst, pseudogap, and superconducting regions. All of the orders appear together at a specific delay time, such as 1.2-3 ps, after pumping by an ultrashort pulse. These discoveries suggest that the Nernst effect, the pseudogap and even superconductivity may have the same physical origin.
Doping dependence of the ultrafast electronic dynamics of Y1-xPrxBa2Cu3O7-delta thin-film superconductors from femtosecond optical spectroscopy
(2010-09-17)
Luo, C. W.
;
Lo, H. P.
;
Su, C. H.
;
Wu, I. H.
;
Chen, Y. -J.
Time-domain spectroscopy, which probes the dynamics of the electronic states near Fermi surface that are associated with superconductivity, has proven to be a powerful method for providing insights into the fundamental nature of both pseudogap and superconducting gap. This study shows that the unique T-x phase diagram with the time-evolving ultrafast dynamics of Y1-xPrxBa2Cu3O7-delta can be used to identify clearly the Nernst, pseudogap, and superconducting regions. All of the orders appear together at a specific delay time, such as 1.2-3 ps, after pumping by an ultrashort pulse. These discoveries suggest that the Nernst effect, the pseudogap and even superconductivity may have the same physical origin.
Simulation of Velocity Distribution and Pressure Drop in Every Channel in the Printed Circuit Heat Exchanger
(2013)
Lo, H. P.
;
Hung, C. H.
;
Wang, C. C.
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機械工程學系
;
Department of Mechanical Engineering
This study examines the performance of printed circuit heat exchangers (PCHE) operated at high temperature subject to the influence of inlet conditions. Simulations are made with three cold plates and three hot plates with mass flow ranging from 0.469kg/h to 4.697kg/h. The inlet temperatures of the cold side and hot side are 200 degrees C and 700 degrees C, respectively. The size of the plate is 272x55x1.65mm with straight channel in the cold side and Z-Shape channel in the hot plate. The simulation is carried out for three cases (Case1: V-c = 5 m/s, T-c = 200 degrees C, V-h = 5 m/s, T-h = 700 degrees C; Case2: V-c = 5 m/s, T-c = 200 degrees C, V-h = 10 m/s, T-h = 700 degrees C; Case3: V-c = 1 m/s, T-c = 200 degrees C, V-h = 5 m/s, T-h = 700 degrees C). It is found that the effect of inlet velocity on the temperature performance is quite significant, and the heat transfer coefficient is related to the mass flow rate. The distribution of mass flow rate within the channel casts significant effect on the outlet temperature. The calculated results indicated the effectiveness epsilon (Case1) is 0.72 which is much higher than those of Case2 (0.704) and Case3 (0.574). Yet the second cold plate shows the maximum temperature difference and the pressure drop in all three cases of simulation.