Browsing by Author "Hsu, CH"

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A distributed charge storage with GeO2 nanodots
(2004-04-05)
Chang, TC
;
Yan, ST
;
Hsu, CH
;
Tang, MT
;
Lee, JF
In this study, a distributed charge storage with GeO2 nanodots is demonstrated. The mean size and aerial density of the nanodots embedded in SiO2 are estimated to be about 5.5 nm and 4.3x10(11) cm(-2), respectively. The composition of the dots is also confirmed to be GeO2 by x-ray absorption near-edge structure analyses. A significant memory effect is observed through the electrical measurements. Under the low voltage operation of 5 V, the memory window is estimated to similar to0.45 V. Also, a physical model is proposed to demonstrate the charge storage effect through the interfacial traps of GeO2 nanodots. (C) 2004 American Institute of Physics.
A genetic algorithm for reliability-oriented task assignment with (k)over-tilde-$ duplications in distributed systems
(2006-03-01)
Chiu, CC
;
Hsu, CH
;
Yeh, YS
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
A distributed system is a collection of processor-memory pairs connected by communication links. The reliability of a distributed system can be expressed using the distributed program reliability, and distributed system reliability analysis. The computing reliability of a distributed system is an NP-hard problem. The distribution of programs & data-files can affect the system reliability. The reliability-oriented task assignment problem, which is NP-hard, is to find a task distribution such that the program reliability or system reliability is maximized. For example, efficient allocation of channels to the different cells can greatly improve the overall network throughput, in terms of the number of calls successfully supported. This paper presents a genetic algorithm-based reliability-oriented task assignment methodology (GAROTA) for computing the (k) over tilde -DTA reliability problem. The proposed algorithm uses a genetic algorithm to select a program & file assignment set that is maximal, or nearly maximal, with respect to system reliability. Our numerical results show that the proposed algorithm may obtain the exact solution in most cases, and the computation time seems to be significantly shorter than that needed for the exhaustive method. When the proposed method fails to give an exact solution, the deviation from the exact solution is very small. The technique presented in this paper would be helpful for readers to understand the correlation between task assignment reliability, and distributed system topology.
A least-squares finite element method for incompressible flow in stress-velocity-pressure version
(1995-12-01)
Chang, CL
;
Yang, SY
;
Hsu, CH
;
交大名義發表
;
National Chiao Tung University
In this paper we are concerned with the incompressible flow in 2-D. Introducing additional variables of derivatives of velocity, which are called stresses here, the second-order dynamic equations are reduced into a first-order system with variables of stress, velocity and pressure. Combining the compatibility condition and the divergence free condition, we have a system with six first-order equations and six unknowns. Least-squares method is performed over this extended system. The analysis shows that this method achieves optimal rates of convergence in the H-1-norm as the h approaches to zero. Numerical experiences are also available.
A least-squares finite element method for incompressible flow in stress-velocity-pressure version
(1995-12-01)
Chang, CL
;
Yang, SY
;
Hsu, CH
;
交大名義發表
;
National Chiao Tung University
In this paper we are concerned with the incompressible flow in 2-D. Introducing additional variables of derivatives of velocity, which are called stresses here, the second-order dynamic equations are reduced into a first-order system with variables of stress, velocity and pressure. Combining the compatibility condition and the divergence free condition, we have a system with six first-order equations and six unknowns. Least-squares method is performed over this extended system. The analysis shows that this method achieves optimal rates of convergence in the H-1-norm as the h approaches to zero. Numerical experiences are also available.
A model of non-homogeneous damped electromagnetic wave and heat equation in ferrite materials
(2002-02-01)
Tung, MJ
;
Chen, R
;
Hsu, CH
;
Tseng, TY
;
電子工程學系及電子研究所
This study uses a closely coupled model to treat the core loss of ferrite by the combination of non-homogeneous damped electromagnetic wave and heat equation. The heat dissipation of ferrites is caused by the core loss, which is a summation of magnetic, dielectric and eddy current losses. Explicit finite difference method solves the coupled equations to calculate core loss and compares it with the measured results. Those results show that this method can be used to analyze electromagnetic and thermal field with temperature dependence of ferrites. (C) 2002 Elsevier Science B.V. All rights reserved.
Abundance of mosaic patterns for CNN with spatially variant templates
(2002-06-01)
Hsu, CH
;
Yang, TH
;
應用數學系
;
Department of Applied Mathematics
This work investigates the complexity of one-dimensional cellular neural network mosaic patterns with spatially variant templates on finite and infinite lattices. Various boundary conditions are considered for finite lattices and the exact number of mosaic patterns is computed precisely. The entropy of mosaic patterns with periodic templates can also be calculated for infinite lattices. Furthermore, we show the abundance of mosaic patterns with respect to template periods and, which differ greatly from cases with spatially invariant templates.
An extended DES
(2002-05-01)
Yeh, YS
;
Hsu, CH
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
The original S-boxes and algorithms of DES are designed to resist differential attack[11]. We propose eight more new S-boxes with the same cryptographic properties as S-boxes in DES. These 16 S-boxes are used to construct the extended DES, which is double the size of the original DES. The differential and linear cryptanalyses of the extended DES are given. The complexities of the two attacks are found to be 2(112) and 2(142) respectively.
Binding effect of surface-modified cadmium sulfide on the microstructure of PS-b-PEO block copolymers
(2004-06-15)
Jeng, US
;
Sun, YS
;
Lee, HY
;
Hsu, CH
;
Liang, KS
CdS nanoparticles with surfaces modified by mercaptoethanol have been synthesized for greater solubility in dimethylformamide (DMF) and the ability to preferentially bind to the poly(ethylene oxide) (PEO) blocks of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymer. The size of the surface-modified CdS nanoparticles (M-CdS) in DMF can be characterized by the Schultz distribution of a mean radius of 18.4 Angstrom and a polydispersity of 0.5, using small-angle X-ray scattering (SAXS). These M-CdS nanoparticles can further disperse in the PS-b-PEO, with a slightly larger mean radius than that observed in DMF. The uptake of M-CdS nanoparticles for the PEO blocks of the PS-b-PEO saturates around 7% in volume fraction. The binding of the nanoparticles promotes a segregation of the PEO/nanoparticles and leads to spherical PEO/M-CdS microdomains in the composite film with a greatly enhanced thermal stability. The structural information obtained from X-ray scattering agrees well with the transmission electron microscopy images and differential scanning calorimetry results.
Cellular neural networks: Local patterns for general templates
(2000-07-01)
Hsu, CH
;
Juang, J
;
Lin, SS
;
Lin, WW
;
應用數學系
This work investigates the mosaic local patterns for cellular neural networks with general templates. Our results demonstrate that the set of templates can be divided into many finite regions. In each region, the same family of local patterns can be generated. Conversely, our results further demonstrate that some templates can realize a family of local patterns which can be linearly separated by a hyperplane in the configuration space. This study also proposes algorithms for verifying the linear separability for a given family of local patterns and, when it is separable, for obtaining the associated template.
Charge-orbital ordering and verwey transition in magnetite measured by resonant soft X-ray scattering
(2006-03-10)
Huang, DJ
;
Lin, HJ
;
Okamoto, J
;
Chao, KS
;
Jeng, HT
We report experimental evidence for the charge-orbital ordering in magnetite below the Verwey transition temperature T-V. Measurements of O K-edge resonant x-ray scattering on magnetite reveal that the O 2p states in the vicinity of the Fermi level exhibit a charge-orbital ordering along the c axis with a spatial periodicity of the doubled lattice parameter of the undistorted cubic phase. Such a charge-orbital ordering vanishes abruptly above T-V and exhibits a thermal hysteresis, correlating closely with the Verwey transition in magnetite.
Charge-orbital ordering of magnetite studied by soft resonant X-ray scattering
(2006-05-01)
Chao, KS
;
Huang, DJ
;
Lin, HJ
;
Okamoto, J
;
Hsu, CH
We report direct experimental evidence for the existence of charge and orbital ordering in magnetite. In particular, measurements of oxygen K-edge resonant X-ray scattering on magnetite reveal that the oxygen 2p states in the vicinity of the Fermi level exhibit a charge-orbital ordering with a spatial periodicity of the doubled lattice parameter of the undistorted cubic phase. (c) 2006 Published by Elsevier B.V.
Composition determination of semiconductor quantum wires by X-ray scattering
(2005-02-28)
Hsu, CH
;
Tang, MT
;
Lee, HY
;
Huang, CM
;
Liang, KS
Self-assembled semiconductor nano-structures, e.g. quantum dots and wires, have recently attracted intensive interests due to their potential applications in optoelectronic industry. Strain field, compositional profile, size, and shape are the key factors determining the physical properties of these nano-structures. However, due to their mesoscopic size, it is a challenge to accurately determine those geometric and chemical parameters. In this work, we present the structural and compositional investigation of GaAs quantum wires grown on InP(0 0 1) substrates by grazing incidence X-ray scattering. In particular, we applied resonant X-ray scattering to determine the compositional distribution within the wires. With properly chosen diffraction peak and X-ray energy range, the profile of energy scan is highly sensitive to the composition of the region with selected lattice constant. As compared to other composition determination methods, which rely on the intensity ratio either between a strong and a weak diffraction or between the same Bragg diffraction collected at different energies, the profile of energy scan is not affected by the significant intensity modulation introduced by inter-wire correlation. Therefore, this method can be applied to systems of various surface morphologies and ordered structures and still provides compositional information with high accuracy and good resolution. (C) 2004 Elsevier B.V. All rights reserved.
Density-controlled carbon nanotubes
(2005-03-01)
Hsu, CH
;
Chen, CF
;
Chen, CC
;
Chan, SY
;
材料科學與工程學系
We demonstrate that the field emission efficiency was greatly improved by reducing the density of carbon nanotubes (CNTs). In this study, catalyst composed of gold and nickel was deposited by e-gun evaporation before pre-treatment of furnace annealing. Carbon nanotubes were then gown on silicon substrate using bias-assisted microwave plasma chemical vapor deposition. Vertical aligned carbon nanotubes were grown with gas mixture of methane and hydrogen under external DC bias. The surface morphology and the tubular structure of carbon nanotubes were confirmed by electron microscopy and the density of carbon nanotubes could be controlled by the composition of the catalyst. The field emission properties were investigated through I-V measurement and the effects are discussed. (c) 2005 Elsevier B.V. All rights reserved.
Devil's staircase of gap maps
(2003-01-01)
Ban, JC
;
Hsu, CH
;
Lin, SS
;
應用數學系
;
Department of Applied Mathematics
This study demonstrates the devil's staircase structure of topological entropy functions for one-dimensional symmetric unimodal maps with a gap inside. The results are obtained by using kneading theory and are helpful in investigating the communication of chaos.
Effects of compressive epitaxial strain on the magnetotransport properties of single-phase electron-doped La0.7Ce0.3MnO3 films
(2004-10-15)
Chang, WJ
;
Hsieh, CC
;
Juang, JY
;
Wu, KH
;
Uen, TM
Single-phase electron-doped manganite thin films with nominal composition of La0.7Ce0.3MnO3 (LCeMO) have been prepared on SrTiO3 (100) substrates by pulsed laser deposition. The conditions for obtaining purely single-phase LCeMO films lie within a very narrow window of substrate temperature (T(s)similar to720 degreesC) and laser energy density (E(D)similar to2 J/cm(2)) during deposition. In situ postdeposition annealing, mainly to relax the possible epitaxial in-plane tensile strain between the film and the substrate, leads to an increasing c-axis lattice constant accompanied by the formation of secondary CeO2 phase and higher metal-insulator transition temperature. This is indicative of a strong coupling between the electron and lattice degree of freedom. (C) 2004 American Institute of Physics.
Effects of growth temperature on solid incorporation of AlAs1-xSbx using tertiarybutylarsine as arsenic source precursor
(1996-10-01)
Chen, WK
;
Ou, JH
;
Hsu, CH
;
交大名義發表
;
電子物理學系
We have investigated the effects of growth temperature on the solid incorporation of AlAsSb epilayers grown LJ metalorganic vapor-phase epitaxy using TMAl, TBAs and TMSb as source precursors. The solid incorporation of AlAsSb was found to be strongly affected by the pyrolysis reactions and kinetics of the source precursors, in particular, TMAl and TBAs. Our experimental results indicated that the, Al incorporation efficiency increases with the growth temperature and saturates at temperatures above similar to 625 degrees C. On the other hand, the growth behavior of As is anomalous: the As incorporation efficiency increases initially with growth temperature, and decreases monotonously at temperatures above similar to 550 degrees C. The reduced As incorporation efficiency at high temperatures may be closely related to the beta-elimination process of TBAs, and to the formation of adducts in the gas phase.
Effects of growth temperature on solid incorporation of AlAs1-xSbx using tertiarybutylarsine as arsenic source precursor
(1996-10-01)
Chen, WK
;
Ou, JH
;
Hsu, CH
;
電子物理學系
;
Department of Electrophysics
We have investigated the effects of growth temperature on the solid incorporation of AlAsSb epilayers grown LJ metalorganic vapor-phase epitaxy using TMAl, TBAs and TMSb as source precursors. The solid incorporation of AlAsSb was found to be strongly affected by the pyrolysis reactions and kinetics of the source precursors, in particular, TMAl and TBAs. Our experimental results indicated that the, Al incorporation efficiency increases with the growth temperature and saturates at temperatures above similar to 625 degrees C. On the other hand, the growth behavior of As is anomalous: the As incorporation efficiency increases initially with growth temperature, and decreases monotonously at temperatures above similar to 550 degrees C. The reduced As incorporation efficiency at high temperatures may be closely related to the beta-elimination process of TBAs, and to the formation of adducts in the gas phase.
Energy, matter, and entropy in evolutionary computation
(1996)
Yang, SMA
;
Sun, CT
;
Hsu, CH
;
資訊工程學系
;
Department of Computer Science
Existence and multiplicity of traveling waves in a lattice dynamical system
(2000-07-01)
Hsu, CH
;
Lin, SS
;
應用數學系
;
Department of Applied Mathematics
This work proves the existence and multiplicity results of monotonic traveling wave solutions for some lattice differential equations by using the monotone iteration method. Our results include the model of cellular neural networks (CNN). In addition to the monotonic traveling wave solutions, non-monotonic and oscillating traveling wave solutions in the delay type of CNN are also obtained. (C) 2000 Academic Press.
Fabrication of NiSi2 nanocrystals embedded in SiO2 with memory effect by oxidation of the amorphous Si/Ni/SiO2 structure
(2005-07-01)
Yeh, PH
;
Wu, HH
;
Yu, CH
;
Chen, LJ
;
Liu, PT
NiSi2 nanocrystals embedded in the SiO2 layer exhibiting a memory effect have been formed by dry oxidation of an amorphous Si/Ni/SiO2 structure at 900 degrees C. A pronounced capacitance-voltage hysteresis was observed with a memory window of I V under the 2 V programming voltage for the samples. For dry oxidation at 800 degrees C, no distinct memory effect was detected. The processing of the structure is compatible with the current manufacturing technology of the semiconductor industry. The structure represents a viable candidate for low-power nanoscaled nonvolatile memory devices. (c) 2005 American Vacuum Society.