Browsing by Author "Hsieh, MC"

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A method to determine the higher order polar anchoring coefficients for the non-twisted liquid crystal cells
(2005-08-01)
Hsu, JS
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Hsieh, MC
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Yang, CL
;
Liang, BJ
;
Chen, SH
We propose a method to determine the higher order polar anchoring coefficients for the non-twisted liquid crystal cells. The surface anchoring energy density was determined by measuring the phase retardations as a function of applied voltage. We extended the Rapini-Papoular model and obtained the coefficients of the first and the second terms by analyzing the measured phase retardations with the simulated curves for the homogeneous and homeotropic cells. A discussion of the experimental results is given.
Effects of oxygen content on the penetration depth in YBCO thin films
(1996)
Hsieh, MC
;
Tseng, TY
;
Fu, CM
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Wu, KH
;
Juang, JY
By varying oxygen content of the microstrip line resonator of YBa2Cu3O7-x, the effective penetration depth was studied. Based on the two-fluid model, we fit the data of the resonant frequency by means of the inductance formula. It allows us to determine the zero-temperature penetration depth of the fully oxygenated,(O approximate to 7) and oxygen deficient (O = 6.8) states in the same strip to be 483.2 nm and 789.8 nm, respectively. The ratio of the superconducting carrier densities with different oxygen contents is then derived and found to be consistent with the result of Hall measurement. A correlation between oxygen contents and charge carriers of the samples will be obtained in our work as accurately as possible.
Effects of oxygen content on the penetration depth of pulsed laser deposited YBCO thin films
(1996-04-01)
Hsieh, MC
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Tseng, TY
;
Wei, SM
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Fu, CM
;
Wu, KH
By systematically varying the oxygen content of microstrip line resonators made of pulsed laser deposited YBa2Cu3O7-x films, the effect of oxygen deficiency on the effective penetration depth were studied. By using the two-fluid model, the zero-temperature penetration depths for the fully oxygenated (i.e. O=7) and oxygen deficient (O=6.8) states in the same strip are found to be 483.2 nm and 789.8 nm, respectively. The large values obtained are attributed to the granular nature of the YBCO films used. The correlation between the penetration depths and superconducting carrier densities as functions of the oxygen content are also discussed.
Fluctuation-enhanced conductivity in YBa2Cu2Ox (6.5 <= x <= 6.95) and Tl2Ba2Ca2Cu3O10 +/-delta
(2000-01-01)
Juang, JY
;
Hsieh, MC
;
Luo, CW
;
Uen, TM
;
Wu, KH
The fluctuation-induced conductivity (Delta sigma(T)) near T-c of a sole YBa2Cu3Ox (YBCO) film with various precisely controlled oxygen contents (6.5 less than or equal to x less than or equal to 6.95) was studied and compared with those obtained from its Tl-based counterparts. For YBCO films with x > 6.7, Delta sigma (T) displays a distinct 3D to 2D crossover as the temperature approaches T-c. On the other hand, as T -->T-c, Delta sigma (T) of both Tl-based and YBCO film with x less than or equal to 6.7 exhibits a reversed 2D to 3D crossover. It is suggestive that the coupling between the CuO2 layers may have changed significantly with reducing oxygen. (C) 2000 Elsevier Science B.V. All rights reserved.
Microwave properties of YBa2Cu3O7-x deposited on MgO substrates
(1997-08-01)
Hsieh, MC
;
Tseng, TY
;
Wu, KH
;
Juang, JY
;
Uen, TM
With pre-annealed treatments, high density of atomic steps were formed on the surface of the MgO substrate. The early-stage microstructure of YBa2Cu3O7-x thin films was evolved with a step-flow growth mode by pulsed laser deposition. On the as-polished MgO substrates the Volmer-Weber-type island growth mode was dominant. By means of microstrip line measurement, it was found that the films grown on the pre-annealed substrate not only have a higher critical current densities but also have a lower microwave loss than those of films deposited on as-polished substrate. The distinction existed even when the deposition condition were not optimized.
Object-oriented programming of adaptive finite element and finite volume methods
(1996-10-01)
Liu, JL
;
Lin, IJ
;
Shih, MZ
;
Chen, RC
;
Hsieh, MC
This article describes an object-oriented implementation of the finite element method and the finite volume method in a unified adaptive system using the programming language C++. The system applies to various types of mathematical model problems. Traditionally, different numerical methods for different types of problems are implemented independently by procedural languages such as C and Fortran. Moreover, adaptive analysis programs are more complicated than nonadaptive programs. Nevertheless, these methods share many common properties such as linear system solvers, data structures, a posteriori error analyses, and refinement processes. Some advantageous features of object-oriented programming are demonstrated through the integration of these properties in the adaptive system. New data types of objects specific to adaptive methods are also introduced. The system is well-structured, extendable, and maintainable due mainly to the nature of encapsulation and inheritance of object-oriented programming.
Object-oriented programming of adaptive finite element and finite volume methods
(1996-10-01)
Liu, JL
;
Lin, IJ
;
Shih, MZ
;
Chen, RC
;
Hsieh, MC
This article describes an object-oriented implementation of the finite element method and the finite volume method in a unified adaptive system using the programming language C++. The system applies to various types of mathematical model problems. Traditionally, different numerical methods for different types of problems are implemented independently by procedural languages such as C and Fortran. Moreover, adaptive analysis programs are more complicated than nonadaptive programs. Nevertheless, these methods share many common properties such as linear system solvers, data structures, a posteriori error analyses, and refinement processes. Some advantageous features of object-oriented programming are demonstrated through the integration of these properties in the adaptive system. New data types of objects specific to adaptive methods are also introduced. The system is well-structured, extendable, and maintainable due mainly to the nature of encapsulation and inheritance of object-oriented programming.
Preparation and electronic properties of YBa2Cu3Ox films with controlled oxygen stoichiometries
(1998-08-01)
Wu, KH
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Hsieh, MC
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Chen, SP
;
Chao, SC
;
Juang, JY
We describe a novel technique capable of controlling the oxygen content of YBa2Cu3Ox (YBCO) films in a precise and reversible manner. The temperature dependence of resistivity and the distinct two-plateau behavior in critical temperature T-CO versus oxygen content plot of these films are consistent with those observed in the bulk and single crystals of YBCO. The O 1s and Cu 2p absorption spectra of these films were measured by polarization-dependent X-ray absorption spectroscopy (XAS). The intensity variations of the pre-edge peaks as a function of oxygen content are discussed. We also used these films to systematically study the electron-phonon coupling strength and the position of Fermi level by using a femtosecond pump-probe technique. A clear sign-reversal of the transient reflectivity, which was consistently explained by the thermomodulation model, was observed. Both of these optical measurements support the idea that the electronic structure of YBCO cuprates is based on the charge transfer model with hybridization between the Cu and O sites.
Solving facility-layout optimization problems with clustering constraints
(1998-03-01)
Li, HL
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Hsieh, MC
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資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Most facility-layout problems are at present solved by heuristic methods, which are not suitable for treating layout problems if some facilities need to be placed together. In this paper we add the constraints of clustering facilities and thus propose an optimization model for facility-layout problems. The advantages of introducing clustering constraints are: first, they fit the more practical rationale of facility layouts; second, they can help improve the computational efficiency owing to the reduction in nonoverlapping constraints among the facilities.