Browsing by Issue Date, starting with "2003-08-01"

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Design and implementation of electromagnetic active control actuators
(2003-08-01)
Bai, MR
;
Ou, KY
;
機械工程學系
;
Department of Mechanical Engineering
We present the modeling, parameter identification and design procedure of a linear voice-coil motor. A numerical simulation has been carried out to facilitate system integration. In particular, we use electromechanical analogy and the time-domain identification procedure with the eigensystem realization algorithm to predict the system response. In order to evaluate the performance of the voice-coil motor, we conducted an experimental investigation. Voice-coil motors mounted on a ball bearing housing are used for generating counter forces to cancel the transverse vibrations of a shaft. A controller is designed by using generalized predictive control. Multiple channel active control systems are implemented on the platform of a digital signal processor. Numerical and experimental results indicated that the designed actuators were effective in suppressing the periodic disturbances in rotors.
Magnetoresistance of La0.7Ca0.3MnO3 thin film biepitaxial step junctions
(2003-08-01)
Chen, SF
;
Chang, WJ
;
Liu, SJ
;
Juang, JY
;
Lin, JY
The biepitaxial La0.7Ca0.3MnO3 (LCMO) thin films grown on SrTiO3 substrates using a buffer layer of anatase TiO2 were fabricated. The magnetoresistance (MR) of biepitaxial step junction (BSJ) across the boundary layer of biepitaxial LCMO (0 0 1) and LCMO (I 10) film was investigated. The temperature and field dependence of MR for BSJ are qualitatively similar to those obtained in other type of artificial grain boundaries with a comparable MR ratio at low temperatures. However, the observed linear current-voltage characteristic across BSJ is in sharp contrary to the commonly reported non-ohmic characteristics. The results are consistent with features predicted by the model of spin-dependent transport across a depressed magnetic ordering and metallic-like junction layer. (C) 2003 Elsevier Science B.V. All rights reserved.
Fabrication and optical property of GaSe thin films grown by pulsed laser deposition
(2003-08-01)
Lee, SH
;
Hsu, YK
;
Hsu, HC
;
Chang, CS
;
Hsieh, WF
The highly oriented (001) GaSe film on c-cut sapphire (0001) was successfully fabricated by pulsed laser deposition. As growth temperature decreases from 550degreesC to 375degreesC, the structure of films changes from cubic zinc-blende Ga2Se3 phase to GaSe phase. The growth temperature of the critical transition from Ga2Se3 phase to GaSe phase is around 500degreesC . From atomic force microscope (AFM) results, it is observed that the growth process of GaSe film is in the manner of layer plus island growth. Besides, the optimal growth conditions of as-grown GaSe film were obtained at a substrate temperature of 400degreesC and laser energy density of 11.7J/cm(2). When the thickness of films goes beyond 800 Angstrom, the stress will be released and the thickness of 1200 Angstrom results in an optimal GaSe film. Furthermore, the indirect bound exciton emission and the recombination via impurity levels or structural defects were observed from low-temperature photoluminescence measurement.
An algorithm for calculating the lower confidence bounds of C-PU and C-PL with application to low-drop-out linear regulators (vol 43, pg 495, 2003)
(2003-08-01)
Pearn, WL
;
Shu, MH
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Fabrication and nonlinear optical properties of nanoparticle silver oxide films
(2003-08-01)
Chiu, Y
;
Rambabu, U
;
Hsu, MH
;
Shieh, HPD
;
Chen, CY
We report the fabrication of nanoparticle silver oxide thin films by rf magnetron sputtering and characterization of their nonlinear optical properties. The chemical decomposition and reversibility of AgOx compounds were studied by thermogravimetric analysis, differential scanning calorimetry, and x-ray diffraction. Electron spectroscopy for chemical analysis measurements revealed a 0.5 eV negative binding energy shift from AgO to Ag2O phase. The effect of particle plasmon resonance was confirmed by the absorption band shift with increased Ag2O Particle size. The measured third-order nonlinear susceptibility (chi(3) = 3.4 x 10(-7) esu) and response time (27 ps) of the Ag2O nanoparticles makes it promising for applications in all-optical switching devices and optical data storage systems. (C) 2003 American Institute of Physics.
Using transforming matrices to generate DNA clone grids
(2003-08-01)
Huang, HM
;
Hwang, FK
;
Ma, HF
;
應用數學系
;
Department of Applied Mathematics
Ina yeast artificial chromosome library, DNA clones may be stored in n-dimensional grids. Barillot, Lacroix and Cohen proposed to use the grid lines as pools in a pooling design (used in physical mapping). To screen the clones in a given grid, they noted that it is important to take several copies of the grid, but rearrange the clones such that two clones are in the same grid line at most once. For ease of implementation, biologists proposed using transforming matrices to transform one copy into another. We give a construction of a set of transforming matrices which produce a maximum number of such copies whenever q is a prime power. (C) 2003 Elsevier B.V. All rights reserved.
Corner sequence - A P-admissible floorplan representation with a worst case linear-time packing scheme
(2003-08-01)
Lin, JM
;
Chang, YW
;
Lin, SP
;
資訊工程學系
;
電子工程學系及電子研究所
Floorplanning/placement allocates a set of modules into a chip so that no two modules overlap and some specified objective is optimized. To facilitate floorplanning/placement, we need to develop an efficient and effective representation to model the geometric relationship among modules. In this paper, we present a P-admissible representation, called corner sequence (CS), for non-slicing floorplans. CS consists of two tuples that denote the packing sequence of modules and the corners to which the modules are placed. CS is very effective and simple for implementation. Also, it supports incremental update during packing. In particular, it induces a generic worst case linear-time packing scheme that can also be applied to other representations. Experimental results show that CS achieves very promising results for a set of commonly used MCNC benchmark circuits.
Electrical characteristics of low temperature polysilicon TFT with a novel TEOS/oxynitride stack gate dielectric
(2003-08-01)
Chang, KM
;
Yang, WC
;
Tsai, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This investigation is the first to demonstrate a novel tetraethylorthosilicate. (TEOS)/oxynitride stack gate dielectric for low-temperature poly-Si (LTPS) thin film transistors (TFTs), composed, of a plasma-enhanced chemical vapor deposition (PECVD) thick TEOS oxide/ultrathin oxynitride grown by. PECVD N2O-plasma. The stack oxide shows a very high electrical breakdown field of 8.4 MV/cm, which is approximately 3 MV/cm larger than traditional PECVD TEOS oxide. The field effective mobility of stack oxide UPS TFTs is over 4 times than that of traditional TEOS oxide UPS TFTs. these. improvements are attributed to the high quality N2O-plasma grown ultrathin oxynitride forming strong Si drop N bonds, as well as to reduce the trap density in the dxynitride/poly-Si interface.
Simultaneous amplitude modulation and wavelength conversion in an asymmetric-duty-cycle periodically poled lithium niobate
(2003-08-01)
Chen, YH
;
Fan, FC
;
Lin, YY
;
Huang, YC
;
Shy, JT
We report the theory and experiment for an amplitude modulator and wavelength converter based on an electrode-coated asymmetric-duty-cycle periodically poled lithium niobate (PPLN). In a 56%/44% domain-duty-cycle PPLN crystal, we modulated the amplitude of the 532-nm second-harmonic output and measured a normalized half-wave voltage of 1.1 V x d (mum)/I-eff (cm), where d is the separation of the electrodes and I-cff is the effective electrode length defined by the PPLN length multiplying the deviation of the domain-duty-cycle from the 50% value. A modulation depth of 85% was obtained in the linear modulation regime. We also derived a unified theory to describe the half-wave voltage for two types of PPLN-based amplitude modulators. (C) 2003 Elsevier Science B.V. All rights reserved.
A hierarchical decimation lattice based on N-queen with an application for motion estimation
(2003-08-01)
Wang, CN
;
Yang, SW
;
Liu, CM
;
Chiang, TH
;
資訊科學與工程研究所
We present a novel technique, N-queen lattice, to spatially subsample a block of pixels. Although this lattice is pertinent to many applications, we present an application to speed up motion estimation with minimal loss of coding efficiency. The N-queen lattice is constructed to characterize spatial features in all directions. It can be hierarchically organized for motion estimation With variable nonsquare block size. Despite the randomized lattice structure, we demonstrate that it is possible to achieve compact data storage architecture for efficient memory access and simple hardware implementation. Our simulations show that the N-queen lattice is superior to several existing sampling techniques with improvement in speed by about N times and small loss. in peak SNR.
Grain-boundary magnetoresistance of CrO2 films grown on TiO2-buffered LaAlO3 substrates
(2003-08-01)
Liu, SJ
;
Juang, JY
;
Wu, KH
;
Uen, TM
;
Gou, YS
The magnetic and magnetotransport properties of predominantly (110)-oriented CrO2 films grown on TiO2-buffered LaAlO3 substrates were investigated. The atomic force microscopic images revealed that the as-grown CrO2 films are granular. The magnetic measurements indicated that in-plane coercive fields are about 60 Oe and 100 Oe at 300 K and 7 K, respectively. The as-grown films are semiconductive below 75 K; a magnetoresistance with a DeltaR/R-0 ratio of -13% in a magnetic field of 5 T was observed at 5 K, which is absent in high-quality epitaxial films. The coincidence between the coercive field and the peaks of the magnetoresistive loop measured at low temperatures indicates that spin-dependent scattering plays a crucial role in the transport properties.
Revisited reparameterization invariance of HQET
(2003-08-01)
Yeh, TW
;
物理研究所
;
Institute of Physics
The heavy quark effective theory is invariant under reparameterization. The specific form of the reparameterization transformation is not unique; and it is closely related to the effective theory. The theory invariant under Luke and Manohar's reparameterization transformation is derived.
A general construction for nonblocking crosstalk-free photonic switching networks
(2003-08-01)
Hwang, FK
;
Lin, WD
;
應用數學系
;
Department of Applied Mathematics
The graph representation G(M) of a multistage switching network M is well known. Lea [IEEE Trans Commun 38 (1990), 529-538] observed that link-disjoint paths in M correspond to node-disjoint paths in G(M). He proposed G(M) as a network by treating nodes as crossbars to transfer the node-disjoint property to the crosstalk-free property essential for photonic networks using directional couplers as components. However, such a network has its peculiarities and is not commonly used. In this paper, we will show how to take advantage of this correspondence to construct nonblocking crosstalk-free networks using the vertical stacking method. Our construction simplifies the proofs of many existing results, as well as establishing some new results. (C) 2003 Wiley Periodicals, Inc.
Integration of CORBA and object relational databases
(2003-08-01)
Liang, KC
;
Chyan, D
;
Chang, YS
;
Lo, WT
;
Yuan, SM
CORBA is widely accepted as the open international standard for modelling and building comprehensive distributed systems. In most cases, CORBA architects have adopted relational databases for storage of persistent data. Among the issues that usually face architecture designers considering how to combine CORBA and standard relational database standards are fault tolerance, performance, and the extensibility and scalability of the systems. The research team involved with this paper found that the ODMG object database concept is useful to solve the issues encountered when integrating CORBA and relational database standards. The reference architecture, which the team devises, integrates CORBA and relational databases without compromise on the necessary transactional properties. The CORBA standard object transaction service and concurrency control service are reused. The team also develop an object relational data modelling tool-Latte-that supports the overall design intention as well the development paradigms for the proposed architecture. The implementation of the system is useful to CORBA, ODMG, and relational database architects because it provides a unified modelling and programming paradigm capable of solving the problems of managing mission-critical distributed data. Thus, we present a case study of combining different international standards to build a comprehensive system. (C) 2003 Elsevier Science B.V. All rights reserved.
Application of perceived value model to identify factors affecting passengers' repurchase intentions on city bus: A case of the Taipei metropolitan area
(2003-08-01)
Jen, W
;
Hu, KC
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
This paper establishes and tests the perceived value model, which is applied to identify the factors affecting the passengers' repurchase intentions on city bus. In this study, perceived value is a trade-off between perceived benefits and perceived costs. And the main part of perceived benefits is service quality. We ( 1) measured service quality using a multiple-items scale, ( 2) integrated perceived non-monetary price as a part of perceived costs, and ( 3) simultaneously incorporated the attractiveness of alternative modes. Data was collected via a questionnaire survey in the Taipei metropolitan area and the model was tested using path analysis performed by LISREL. The results indicate that all causal relationships are statistical significant. Finally, this study concludes by discussing managerial implications and making suggestions for future research.
Thickness dependence of microstructure of laterally crystallized poly-Si thin films and electrical characteristics of low-temperature poly-Si TFTs
(2003-08-01)
Chang, TK
;
Lin, CW
;
Chang, YH
;
Tseng, CH
;
Chu, FT
The effects of thickness of a-Si thin films on the resulting microstructure of metal-induced laterally crystallized (MILC) poly-Si and electrical characteristics of MILC low temperature poly-Si (LTPS) thin film transistors (TFTs) were investigated. The TEM images revealed a double-layer structure in the 1000-Angstrom MILC poly-Si thin film. However, for the 400-Angstrom MILC poly-Si thin film, there were single-layer grains within the thin film layer. The reason has been ascribed to the geometry restriction in the crystallization procedure. The average mobility of fabricated MILC LTPS TFTs with active layer thickness of 400 Angstrom showed a little higher than that with 1000 Angstrom active layer. Moreover, the MILC LTPS TFTs with active layer thickness of 400 Angstrom exhibited better electrical uniformity than those with 1000 Angstrom active layer either in threshold voltage or field-effect mobility. The reason should also be attributed to the different crystalline structures within the two thin-film layers. (C) 2003 The Electrochemical Society.
High quality Al2O3IPD with NH3 surface nitridation
(2003-08-01)
Chen, YY
;
Chien, CH
;
Lou, JC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this letter, the effect of surface NH3 nitridation on the electrical properties and reliability characteristics of aluminum oxide (Al2O3) interpoly capacitors is studied. With NH3 surface nitridation, the formation of an additional layer with lower dielectric constant during post-annealing process can be significantly suppressed, compared to that without nitridation treatment. Furthermore, the presence of a thin Si-N layer can make post-deposition annealing more effective in eliminating traps existing in the as-deposited films. As a result, a smoother interface and smaller electron trapping rate can contribute to the drastically reduced leakage current, enhanced breakdown field and charge to breakdown (Q(bd)) of Al2O3 interpoly capacitors with surface NH3 nitridation.
Orthometric corrections from leveling, gravity, density and elevation data: a case study in Taiwan
(2003-08-01)
Hwang, C
;
Hsiao, YS
;
土木工程學系
;
Department of Civil Engineering
A new orthometric correction (OC) formula is presented and tested with various mean gravity reduction methods using leveling, gravity, elevation, and density data. For mean gravity computations, the Helmert method, a modified Helmert method with variable density and gravity anomaly gradient, and a modified Mader method were used. An improved method of terrain correction computation based on Gaussian quadrature is used in the modified Mader method. These methods produce different results and yield OCs that are greater than 10 cm between adjacent benchmarks (separated by similar to2 km) at elevations over 3000 in. Applying OC reduces misclosures at closed leveling circuits and improves the results of leveling network adjustments. Variable density yields variation of OC at millimeter level everywhere, while gravity anomaly gradient introduces variation of OC of greater than 10 cm at higher elevations, suggesting that these quantities must be considered in OC. The modified Mader method is recommended for computing OC.
滿臉梨花詞
(2003-08-01)
管管
A tunable S-band erbium-doped fiber ring laser
(2003-08-01)
Yeh, CH
;
Lee, CC
;
Chi, S
;
光電工程學系
;
Department of Photonics
In this paper, we experimentally investigate and demonstrate an S-band erbium-doped fiber (EDF) ring laser based on an erbium-doped silica fiber and 980-nm pumping laser. Widely tunable range from 1480 to 1522 run, and the sidemode suppression ratio (SMSR) of >30 dB/0.1 nm and the output power of > -2 dBm in the operating range from 1482 nm to 1517 nm have been achieved for this ring laser. Under the constant power control, the output power variation less than +/-0.05 dB can also be accomplished over the tuning range from 1482 to 1517 run. This S-band EDF ring laser is promising for the future S-band applications.