Browsing by Author "Liu, W. Z."

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Analysis of filling of an oval disk-shaped chamber with microfluidic flows
(2006-11-20)
Chen, J. J.
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Liu, W. Z.
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Lin, J. D.
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Wu, J. W.
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機械工程學系
The filling of an oval disk-shaped micro-chamber by liquid is analyzed with reference to micro-systems with inlets and outlets of various widths, which are fabricated using MEMS technology. The results concern the motion of the gas-liquid interface. The flow fields during the filling of the micro-chambers are also studied. During the filling, the front shape is determined by the competition among inertia, adhesion and surface tension. The effects of non-dimensional parameters, such as the Reynolds number and the Weber number, both determine by the inlet velocity, as well as the wall adhesive conditions, on the flow characteristics are examined. The effects of the widths of channels in a circular chamber and the lengths of the semi-major and semi-minor axes of an oval chamber on the filling process are also investigated. Geometric changes alter the angle between the microchannels and the micro-chamber at their intersection and significantly affect the filling of the micro-chamber with the liquid. The location of bubble entrapment is plotted parametrically against the Weber number, the liquid/substrate contact angle and the change in the angle between the microchannels and the micro-chamber at intersection. Evidently, air is entrapped when the inertia is high, large changes in the angle between the channels and the chamber at the intersection are made, and a hydrophobic property is observed inside the chamber wall. The numerical results are also compared with experimental measurements; they indicate similar filling processes. (c) 2006 Elsevier B.V. All rights reserved.
Distribution of electronic reconstruction at the n-type LaAlO(3)/SrTiO(3) interface revealed by hard x-ray photoemission spectroscopy
(2011-12-26)
Chu, Y. Y.
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Liao, Y. F.
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Tra, V. T.
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Yang, J. C.
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Liu, W. Z.
We investigated the electronic reconstruction at the n-type LaAlO(3)/SrTiO(3) interface with hard x-ray photoelectron spectroscopy (HAXPES) under grazing incidence. By exploiting the collapse of evanescent x-ray waves and the abrupt increase of x-ray absorption at the critical incidence angle, our HAXPES study reveals a 2% electronic reconstruction from Ti(4+) to Ti(3+) occurring near the interface. Such an electronic reconstruction also extends from the interface into SrTiO(3) with a depth of about 48 angstrom (similar to 12 unit cells) and an estimated total charge transfer of similar to 0.24 electrons per two-dimensional unit cell. (C) 2011 American Institute of Physics. [doi:10.1063/1.3672099]
Distribution of electronic reconstruction at the n-type LaAlO3/SrTiO3 interface revealed by hard x-ray photoemission spectroscopy
(2011-12-26)
Chu, Y. Y.
;
Liao, Y. F.
;
Tra, V. T.
;
Yang, J. C.
;
Liu, W. Z.
We investigated the electronic reconstruction at the n-type LaAlO3/SrTiO3 interface with hard x-ray photoelectron spectroscopy (HAXPES) under grazing incidence. By exploiting the collapse of evanescent x-ray waves and the abrupt increase of x-ray absorption at the critical incidence angle, our HAXPES study reveals a 2% electronic reconstruction from Ti4+ to Ti3+ occurring near the interface. Such an electronic reconstruction also extends from the interface into SrTiO3 with a depth of about 48 angstrom (similar to 12 unit cells) and an estimated total charge transfer of similar to 0.24 electrons per two-dimensional unit cell. (C) 2011 American Institute of Physics. [doi:10.1063/1.3672099]