Browsing by Issue Date, starting with "2003-01-11"

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靜電驅動微機電裝置之控制系統
(2003-01-11)
邱俊誠
;
林育成
本發明有關一種靜電驅動微機電裝置之控制系統，其利用多塊電極板來控制靜電驅動微機電裝置，亦即，將熟知兩平行板驅動電極之電容器的下方驅動電極板切割為若干小的電極板，藉選擇用於所企望之靜電力的電極板圖案，可根據不同的應用改變裝置之非線性而取得諸如線性驅動，數位驅動，或最佳化驅動之特性，使能在裝置具有有限精確度之先天限制下達成高度的操作精確性。
Novel oxadiazole-containing polyfluorene with efficient blue electroluminescence
(2003-01-14)
Wu, FI
;
Reddy, DS
;
Shu, CF
;
Liu, MS
;
Jen, AKY
A novel oxdiazole-containing polyfluorene copolymer (PF-OXD) was synthesized by attaching two electron-deficient, 4-tent-butylphenyl-1,3,4-oxadiazole groups onto the C-9 position of the alternating fluorene unit to form a 3-D cardo-structure. This polymer possesses a very high glass transition temperature (T-g: 213 degreesC) and very good thermal stability due to its rigid cardo-linkage. The results from the photoluminescence measurements of the isothermally heated PF-OXD thin film (150 degreesC for 20 h) show that the commonly observed aggregate/excimer formation in polyfluorenes is very effectively suppressed in this polymer due to its 3-D structure and high T-g. A double-layer LED device using this polymer as the emitting layer shows a bright blue emission with a low turn-on voltage at 5.3 V and a high brightness of 2770 cd/m(2) at a drive voltage of 10.8 V. The maximum external quantum efficiency is 0.52% at 537 cd/m(2) with a bias of 7.4 V. The improved device performance over that of poly(9,9-dioctylfluorene) (POF) may be due to better electron injection and transport in PF-OXD and the efficient energy transfer from the OXD side chain to the polyfluorene main chains.
Ion exchange accompanied by neutralization in an anion bed
(2003-01-15)
Tan, HKS
;
應用化學系
;
Department of Applied Chemistry
The performance of the anion bed in a two-bed deionization process was investigated. Experiments and simulation were carried out with a feed solution concentration of about 0.005N. The prepared solutions were dilute acid of HCl, H2SO4 and a mixture of the two. The bed height was about 40 cm and the flow rate in the range of 75-150 ml/min. Both the binary and ternary models were used to predict the column performance. In both models, it was found that the equilibrium parameters do not affect significantly the breakthrough behavior. This is due to the accompanied neutralization reaction which results in the irreversible form of the rate equation. The experimental and theoretical breakthrough curves show very good agreement especially for the early part of the data. Results of this study suggest that a pseudo-binary or pseudo-ternary model can be used to model the fixed bed deionization process by ion exchange. (C) 2002 Elsevier Science B.V. All rights reserved.
Chaos, chaos control and synchronization of electro-mechanical gyrostat system
(2003-01-16)
Ge, ZM
;
Lin, TN
;
機械工程學系
;
Department of Mechanical Engineering
The dynamic behavior of electro-mechanical gyrostat system subjected to external disturbance is studied in this paper. By applying numerical results, phase diagrams, power spectrum, Period-T maps, and Lyapunov exponents are presented to observe periodic and chaotic motions. The effect of the parameters changed in the system can be found in the bifurcation and parametric diagrams. Several methods, the delayed feedback control, adaptive control algorithm (ACA) control are used to control chaos effectively. Anticontrol of chaos destroyed the periodic motions and replaced by chaotic motion effectively by adding constant motor torque and adding periodic motor torque. Finally, synchronization of chaos in the electro-mechanical gyrostat system is studied. (C) 2002 Elsevier Science Ltd. All rights reserved.
街小說
(2003-01-16)
管管
Analysis of nonuniform and dispersive time domain reflectometry measurement systems with application to the dielectric spectroscopy of soils
(2003-01-18)
Lin, CP
;
土木工程學系
;
Department of Civil Engineering
[1] A practical time domain reflectometry (TDR) measurement system consists of a cable tester and a nonuniform transmission line. The transmission line includes a coaxial cable, a transitional device, and a measurement probe. Dielectric spectroscopy in a nonuniform transmission line requires a wave propagation model that accounts for multiple reflections in a nonuniform and dispersive TDR measurement system. Spectral analysis and the concept of input impedance were utilized to develop such a model. The system parameters were calibrated using the measured TDR waveform in an aqueous material with known dielectric permittivity. The excellent match between the simulated and measured waveforms validated the wave propagation model. A layer-peeling algorithm was developed, based on the new formulation of the wave propagation model to remove the effect of the cable and transitional device on the measurement by TDR. The dielectric spectrum obtained by solving the scatter function was compared with that obtained by matching waveforms based on a dielectric relaxation model. The latter method was confirmed by the experimental results as being superior to the former at high frequencies if an appropriate dielectric relaxation model was used. Both the Debye relaxation model and the volumetric mixing model could model the dielectric dispersion of soils in the TDR frequency range. The latter method outperforms the former in modeling the dielectric dispersion of soils over the full range of frequencies.
A 1.2-V fully integrated 2.4-GHz low-noise amplifier in 0.35-mu m CMOS technology
(2003-01-20)
Meng, CC
;
Chiang, MH
;
Wu, TH
;
電信工程研究所
;
Institute of Communications Engineering
A 1.2-V fully integrated 0.35-mum inductively degenerated common source CMOS low-noise amplifier has been demonstrated at 2.4 GHz in this paper. A simple common source configuration can be operated at lower voltage and has lower output impedance when compared with a conventional high output impedance cascode LNA circuit topology. The input matching inductance, output matching inductance, and source degeneration inductance are integrated on a single chip. The fully integrated 2.4-GHz CMOS LNA has 5.27-dB power gain, 17-dB input return loss, 15413 output return loss, 4-dB noise figure, and -1-dBm IIPIdB and 8-dBm IIP3 at V-dd = 1.2 V and I-dd = 10 mA, respectively. (C) 2003 Wiley Periodicals, Inc.
A novel method for short leaky-wave antennas to suppress the reflected wave
(2003-01-20)
Wang, CJ
;
Guan, HL
;
Jou, CF
;
傳播研究所
;
Institute of Communication Studies
A method to suppress the back lobe of a short leaky-wave antenna (LWA) by using an aperture-fed patch antenna on the backside is demonstrated in this paper. The aperture-fed patch antenna is connected to the open end of the LWA. This design offers another radiation path of the reflected wave and creates another radiation pattern on the back plane of the substrate. Experimental results show that the suppression of the reflected wave can be 10 dB at 10.0 GHz with an LWA length of 6 cm (2 wavelengths). Compared to the conventional design, this novel structure can radiate as efficiently as LWA at a length a wavelengths. The two radiation patterns on different planes have great potential in many applications and can provide more flexibility to traditional designs. (C) 2003 Wiley Periodicals, Inc.
Identification and characterization of KvgAS, a two-component system in Klebsiella pneumoniae CG43
(2003-01-21)
Lai, YC
;
Lin, GT
;
Yang, SL
;
Chang, HY
;
Peng, HL
A two-component system encoding gene cluster kvgAS that is present only in virulent Klebsiella pneumoniae CG43 was isolated and its sequence determined. RT-PCR and Southern analysis demonstrated that kvgAS is organized as an operon. No apparent effect of a kvgS deletion on bacterial virulence was observed in a mouse peritonitis model. In the presence of paraquat or 2,2-dipyridyl, the activity of kvgAS promoter in the kvgS mutant was found to be reduced to half of the level in the wild-type strain. The data suggest that the KvgAS system is autoregulated and plays a role in countering free radical stresses and sensing iron-limiting conditions. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.
Overflow control in mobile communication using N-class replacement
(2003-01-23)
Sue, KL
;
Lo, CC
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
A strategy called N-class replacement (NR) policy is proposed to overcome visitor location register (VLR) overflow in a mobile communication system. The NR policy requires only few bits in the VLR record. It is feasible for separated VLR databases in real mobile networks. For the rate of excellent replacement, the simulation results show that the NR policy outperforms currently proposed policies.
Triplet-to-singlet exciton formation in poly(p-phenylene-vinylene) light-emitting diodes
(2003-01-24)
Lin, LC
;
Meng, HF
;
Shy, JT
;
Horng, SF
;
Yu, LS
The triplet to singlet exciton formation ratio in a MEH-PPV light-emitting diode is measured by comparing the triplet-induced absorptions with optical and electric excitations at the same singlet exciton density. The ratio is a strong universal decreasing function of the averaged electric field. Using 4 ns for singlet to triplet intersystem crossing time, the ratio is significantly larger than the spin-independent value 3 at intermediate field but is reduced to about 2 for higher field.
Preparation and cathodoluminescence of ZnO phosphor
(2003-01-30)
Lin, CH
;
Chiou, BS
;
Chang, CH
;
Lin, JD
;
電子工程學系及電子研究所
Zinc oxide phosphors (ZnO:Zn) were prepared with solid state sintering of ZnO powders with ZnS and screen printed onto ITO-coated glass substrates to form a thin layer. Structural characterization carried out by X-ray diffraction (XRD) analysis suggests that the Zn atoms originated from the decomposition of ZnS, and diffuse to occupy the oxygen vacancies in the host lattice. Both lattice parameters a and c decrease slightly with the increase of ZnS content and/or firing temperature. The cathodoluminescent (CL) peak band varies with ZnS content and ranges from 494 to 508 nm, which is close to the green band of ZnO phosphor. Various mechanisms have been proposed in literatures to explain the origin of the green emission band. Among them, the presence of oxygen vacancies and trace ZnS residue are possible causes for the green emission in this study. CL spectra and CIE color loci suggest that ZnO:Zn phosphor with 5 wt.% ZnS can be. used as a green primary for color picture tubes. (C) 2002 Elsevier Science B.V. All rights reserved.
Role of an intermediate phase (Ba,Sr)(2)Ti2O5CO3 in doped (Ba0.7Sr0.3)TiO3 thin films
(2003-01-30)
Chen, SY
;
Wang, HW
;
Huang, LC
;
材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba0.7Sr0.3)TiO3 (BST) thin films doped with La, Nb, and Mg ions were prepared by metal-organic deposition method (MOD) on Pt/Ti/SiO2/Si substrates. An intermediate phase formed under an annealing temperature of 550-650 degreesC, and disappeared at higher temperatures during the formation of BST. The intermediate phase was analyzed by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR) and Raman spectra and found to be an oxycarbonate with a chemical formula of (Ba,Sr)(2)TiO5CO3. The stability of this intermediate phase increased with the addition of dopants, irrespective of doping types. It is proposed that distortion of crystal structure, physical constraint in the two-dimensions and small grain size favor the existence of poor crystallized (Ba,Sr)(2)Ti2O5CO3. (C) 2002 Elsevier Science B.V. All rights reserved.
Atomistics of Ge deposition on Si(100) by atomic layer epitaxy
(2003-01-31)
Lin, DS
;
Wu, JL
;
Pan, SY
;
Chiang, TC
;
物理研究所
Chlorine termination of mixed Ge/Si(100) surfaces substantially enhances the contrast between Ge and Si sites in scanning tunneling microscopy observations. This finding enables a detailed investigation of the spatial distribution of Ge atoms deposited on Si(100) by atomic layer epitaxy. The results are corroborated by photoemission measurements aided by an unusually large chemical shift between Cl adsorbed on Si and Ge. Adsorbate-substrate atomic exchange during growth is shown to be important. The resulting interface is thus graded, but characterized by a very short length scale of about one monolayer.
An all-digital phase-locked loop for high-speed clock generation
(2003-02-01)
Chung, CC
;
Lee, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An all-digital phase-locked loop (ADPLL) for high-speed clock generation is presented in this brief. The proposed ADPLL architecture uses both a digital control mechanism and a ring oscillator and, hence, can be implemented with standard cells. The ADPLL implemented in a 0.3-mum one-poly-four-metal CMOS process can operate from 45 to 510 MHz and achieve worst case frequency acquisition in 46 reference clock cycles. The power dissipation of the ADPLL is 100 mW (at 500 MHz) with a 3.3-V power supply. From chip measurement results, the P-k-P-k jitter of the output clock is < 70 ps; and the root-mean-square jitter of the output clock is < 22 ps. A systematic way to design the ADPLL with the specified standard cell library is also presented in this brief. The proposed ADPLL can easily be ported to different processes in a short time. Thus, it can reduce the design time and design complexity of the ADPLL, making it very suitable for system-on-chip applications.
Low temperature radio-frequency-sputtered (Ba, Sr)TiO3 films on Pt/TiN/Ti/Si substrates with various oxygen/argon mixing ratios
(2003-02-01)
Shye, DC
;
Chiou, BS
;
Lai, MJ
;
Hwang, CC
;
Jiang, CC
(Ba, Sr) TiO3 (BST) films were fabricated on Pt/TiN/Ti/Si substrates by low temperature radio frequency magnetron cosputtering at 300degreesC. Material and electrical properties of BST films sputtered at low temperatures are significantly affected by the O-2/(Ar + O-2) mixing ratio (OMR). Plasma emission spectra indicate that the deposition rate declines at a higher OMR due to oxide formation on the target surface. The dielectric constant of the BST films can reach a maximum of 364 at 5% OMR. The ten-year lifetime of the time-dependent dielectric breakdown implies that the reliability of the capacitor can be enhanced at a higher OMR due to compensation of oxygen vacancies and smaller grain sizes. Current-voltage analysis indicates that the leakage current of the Pt/BST/Pt capacitor is limited by Schottky emission (SE)/Poole-Frenkel emission (PF) at a lower/higher applied field. The applied field boundary between SE and PF shifts toward higher field as OMR increases. Moreover, an energy band model was proposed and this leakage mechanism was discussed. (C) 2003 The Electrochemical Society.
Co-evolution as a computational and cognitive model of design
(2003-02-01)
Maher, ML
;
Tang, HH
;
建築研究所
;
Institude of Architecture
Co-evolutionary design has been developed as a computational model that assumes two parallel search spaces: the problem space and the solution space. The design process iteratively searches each space using the other space as the basis for a fitness function when evaluating the alternatives. Co-evolutionary design can also be developed as a cognitive model of design by characterizing the way in which designers iteratively search for a design solution, making revisions to the problem specification. This paper presents the computational model of co-evolutionary design and then describes a protocol study of human designers looking for evidence of co-evolution of problem specifications and design solutions. The study shows that co-evolutionary design is a good cognitive model of design and highlights the similarities and differences between the computational model and the cognitive model. The results show that the two kinds of co-evolutionary design complement each other, having strengths in different aspects of the design process.
Thermochromism of silver oxide for optical switching layers in volumetric optical disks
(2003-02-01)
Wu, FH
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
For reading and writing on a lower targeted recording layer of volumetric optical disks, transmitted laser power is decreased by absorption and reflection of the upper layers. Thus, a layer of thermo-chromatic material, such as silver oxide, has been added as an optical switching layer next to the recording layers to modulate the optical characteristics of the recording layers by the diffraction limited laser beam during writing. The optical switching structure can reduce peak writing laser energy by 42%. Consequently, optical switching layer is promising for volumetric recording to optimize R/W performance.
Effect of aging treatment on the mechanical properties of C-250 maraging steel by flow forming
(2003-02-01)
Lee, IK
;
Chou, CP
;
Cheng, CM
;
Kuo, IC
;
機械工程學系
The technique of forward flow forming has been used to produce a long, thin walled tube made of C-250 maraging steel. The forward flow forming can save raw material, increase strength, and reduce the production process time. Because the work hardening effect on solution-treated C-250 using flow forming is minimal, the flow-formed tube requires an additional heat treatment to obtain higher hardness and strength. With the direct aging treatment, low elongation values are obtained, making this treatment unsuitable for the engineering design. It was found that the 540 degreesC/6 h/AC over-aging treatment results in better strength and elongation values. The strengthening phase of the flow-formed C-250 maraging steel was found to be the intermetallic compound of Fe3Mo.
BCS-like superconductivity in MgCNi3
(2003-02-01)
Lin, JY
;
Ho, PL
;
Huang, HL
;
Lin, PH
;
Zhang, YL
The low-temperature specific heat C(T,H) of the superconductor MgCNi3 has been measured in detail. DeltaC/gamma(n)T(c)=1.97 is estimated from the anomaly at T-c. At low temperatures, the electronic contribution in the superconducting state follows C-es/gamma(n)T(c)approximate to7.96 exp(-1.46T(c)/T). The magnetic-field dependence of gamma(H) is found to be linear with respect to H. T-c estimated from the McMillan formula agrees well with the observed value. All the specific-heat data appear to be consistent with each other within the moderate-coupling BCS context. It is amazing that such a superconductor unstable to ferromagnetism behaves so conventionally. The Debye temperature Theta(D)=287 K and the normal state gamma(n)=33.6 mJ/mol K-2 are determined for the present sample.