Browsing by Issue Date, starting with "2003-09-20"

Now showing 1 - 20 of 72319

Linewidth reduction and wavelength tuning of an erbium-doped fiber laser by use of a single-mode-selected and side-mode-suppressed Fabry-Perot laser diode
(2003-09-20)
Lin, GR
;
Wu, JR
;
光電工程學系
;
Department of Photonics
A single-mode and highly side-mode-suppressed 1.55-mum Fabry-Perot laser diode (FPLD) is achieved by feedback injection with an erbium-doped fiber laser (EDFL). For selection of the strongest longitudinal mode from the gain spectrum of the FPLD for lasing in the EDFL, the FPLD is operated at just below the threshold condition and is feedback injected by 0.02% of the EDFL output power. The lasing mode and center wavelength of the proposed single-mode FPLD source are decided by cross-correlated gain profiles of the EDFL and the FPLD; however, the effect of FPLD injection modes is found to be more pronounced. The optimized lasing linewidth (system limitation) and side-mode suppression ratio of 0.01 nm and >49 dB are obtained, which are far better than those of a FPLD at free-running condition. The worst linewidths at 3- and 10-dB decay are observed to be at approximately 0.016 and 0.05 nm, respectively. Linear wavelength tuning of as much as 4.5 nm (from 1558.7 to 1563.2 nm) by adjustment of the temperature of the FPLD from 10 degreesC to 40 degreesC at just below threshold is reported. The wavelength-tuning slope is approximately 0.14 nm/degreesC under temperature accuracy of 0.1 degreesC. (C) 2003 Optical Society of America.
Diode-pumped passively mode-locked multiwatt Nd : GdVO4 laser with a saturable Bragg reflector
(2003-09-20)
He, JL
;
Lee, CK
;
Huang, JYJ
;
Wang, SC
;
Pan, CL
We report a first demonstration, to our knowledge, of a cw passively mode-locked Nd:GdVO4 laser (lambda = 1063 nm). A relaxed saturable Bragg reflector was used. The laser generates pulses of 9.2 ps at a repetition rate of 119 MHz. As much as 5.4 W of average power was realized with a slope efficiency of 25.7%. (C) 2003 Optical Society of America.
鐵電場效電晶體製造方法
(2003-09-21)
陳三元
;
孫嘉良
;
荊鳳德
本案係指一種鐵電場效電晶體製造方法，其係應用於金屬/鐵電薄膜/絕緣層/半導體(MFIS)結構的閘極電容元件製作上，該方法乃藉由在該絕緣層上沈積一鉍系鐵電薄膜，並經由一高溫熱處理後，再鍍上一上電極層於該鉍系鐵電薄膜上，俾得致該鐵電場效電晶體結構。
Effect of thermal annealing of Ni/Au ohmic contact on the leakage current of GaN based light emitting diodes
(2003-09-22)
Hsu, CY
;
Lan, WH
;
Wu, YS
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The effect of thermal annealing on current-voltage properties of GaN light emitting diodes (LEDs) has been studied. At annealing temperatures above 700 degreesC, the p-n junction of the diodes became very leaky and Ga-contained metallic bubbles were observed on the surface of Ni/Au p-ohmic contact. Transmission electron microscopy and energy dispersive x-ray spectrometer studies revealed that these metallic bubbles resided directly on top of the threading dislocations in GaN and both Ni and Au were indiffused into the LED structure along the cores of the TDs. The conducting paths formed by the metal containing dislocation cores are believed to be the cause for the observed short circuit behavior of p-n junctions at high annealing temperatures. (C) 2003 American Institute of Physics.
4-(Dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran doped red emitters in organic light-emitting devices
(2003-09-22)
Liu, TH
;
Iou, CY
;
Wen, SW
;
Chen, CH
;
應用化學系
We have studied the device optimization of red 4-(Dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) dye doped Alq(3) emitters in organic light-emitting devices (OLED). By varying the hole injection materials, thickness of hole-transport layer and by evaporation with rubrene as co-dopant, efficiencies of 3.24 cd/A and near saturated CIE color coordinates of x = 0.643, y = 0.354 was achieved without needing additional doping of hole-trap with NPB. From experiments with film thickness variation, it is concluded that the improved electrofluorescent (EL) performance and color saturation are due to the synergistic effects of microcavity, device structural optimization as well as optimal doping of DCJTB with rubrene. We believe this luminance efficiency for red is by far one of the best ever reported for dye-doped electrofluorescent OLEDs. (C) 2003 Elsevier B.V. All rights reserved.
Polyimide-side-chain tethered polyhedral oligomeric silsesquioxane nanocomposites for low-dielectric film applications
(2003-09-23)
Leu, CM
;
Chang, YT
;
Wei, KH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Low-dielectric-constant nanoporous films (dielectric constant, k = 2.4) with thermal integrity and controllable mechanical strength have been prepared by covalently tethering nanoporous polyhedral oligomeric silsesquioxane (POSS) molecules, 1-nm size, to the side chains of polyimide. The tethered POSS molecules in the amorphous polyimide retain a nanoporous crystal structure, but form an additional ordered architecture due to microphase separation. With this approach, the dielectric constant of the film can be tuned by the amount of POSS molecules introduced in the nanocomposite film; the polyimide molecules offer additional advantages of maintaining certain thermal and mechanical strengths.
Blocking the dengue virus 2 infections on BHK-21 cells with purified recombinant dengue virus 2 E protein expressed in Escherichia coli
(2003-09-26)
Chiu, MW
;
Yang, YL
;
生物科技學系
;
Department of Biological Science and Technology
Dengue viruses (DVs) are mosquito-borne infectious pathogens. They have become an expanding public health problem in the tropics and subtropics. The dengue envelope (E) protein is one of the viral structure proteins responsible mainly for the virus attachment and entry onto host cells. It is also the major immunogen for virus neutralization. In this study, we have constructed a recombinant plasmid expressing a truncated E protein of DV-2 virus PL046 strain: The C-terminal hydrophobic domain of the E protein was removed and replaced with the sequence of S peptide to facilitate expression and purification. When expressed in Escherichia coli, the recombinant E proteins were found to be in the form of aggregated state. Through denaturation and dialysis processes, the receptor-interacting function of the purified recombinant E proteins was maintained, which was demonstrated by its ability to inhibit the DV-2 plaque-forming efficiency on mammalian BHK-21 host cells. (C) 2003 Elsevier Inc. All rights reserved.
Molecular sublayers beneath the air-sea interface relative to momentum, heat and gas transports
(2003-09-27)
Tsai, WT
;
Chen, SM
;
Lin, MY
;
Hung, LP
;
土木工程學系
Numerical simulations of the wind-driven aqueous turbulent flow and the underlying heat and dissolved gas transports are conducted with sufficiently fine grid resolution to resolve the molecular sublayers immediately beneath the air-water interface. The simulated mean distributions of velocity, temperature and gas concentration all exhibit exponential profiles across the sublayers in accordance with the theoretical postulation of Liu and Businger [1975] which they derived on the basis of the conceptual surface renewal model. The numerical results identify two major coherent renewal processes within the flow: intermittent upwellings induced by uprising horseshoe-like eddies in the well-mixed region, and elongated, high-speed, cool streaks within the sublayer reflecting the cool-skin thermal structure.
Realization of transmission zeros in combline filters using an auxiliary inductively coupled ground plane
(2003-10-01)
Tang, CW
;
Lin, YC
;
Chang, CY
;
電信工程研究所
;
Institute of Communications Engineering
The out-band transmission zeros of the multilayer low-temperature co-fired ceramic bandpass filter are studied in this paper. The design target of this filter, with the passband between 2.3-2.65 GHz (the true application is 2.4-2.483 GHz), is to reject the local oscillator and image signals and, in the mean time, to suppress the harmonic frequency. This filter is a modified three-pole combline filter, which can easily achieve a high rejection rate and low insertion loss. The source-load coupling capacitor incorporation with cross-coupling grounding inductors can generate three transmission zeros. By properly adjusting the inductance values of the inductors between three resonators and ground can easily manipulate the transmission zero at a high-side skirt to suppress the harmonic frequency. The measured results match well with the electromagnetic simulation that evidences the feasibility of the proposed design.
Relationship between protein structures and disulfide bonding patterns
(2003-10-01)
Chuang, CC
;
Chen, CY
;
Yang, JM
;
Lyu, PC
;
Hwang, JK
We found that that disulfide-bonding patterns can be used to discriminate structure similarity. Our method, based on the hierarchical clustering scheme, is applicable to proteins with two or more disulfide bonds and is able to detect the structural similarities of proteins of low sequence identities (<25%). Our results show the surprisingly close relationship between disulfide-bonding patterns and proteins structures. Our findings should be useful in protein structure modeling. (C) 2003 Wiley-Liss, Inc.
Synthesis and characterization of needlelike apatitic nanocomposite with controlled aspect ratios
(2003-10-01)
Liou, SC
;
Chen, SY
;
Liu, DM
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Calcium-deficient apatitic (cd-HA) crystals with core-shell nanostructure with needlelike shape, 5-10nm in diameter and 2080 nm in length. were prepared via an in situ formation in the presence of polyacrylic acid (PAA) under aqueous solution of different pH values. ranging from 9 to 11. Nanostructure of the resulting crystals showing a core-shell configuration with a thin layer of PAA shell of about I rim thickness was investigated. Aspect ratio (AR) of the needlelike composite was found to depend on the concentration of the PAA and solution pH. At lower solution pH crystal growth was inhibited, i.e., leading to a decreased AR, with increase of PAA concentration. while an increased AR was detected at higher solution pH, suggesting a preferential growth of the cd-HA nanocrystals. Mechanism of such preferential growth was tentatively proposed and is suggested to correct PAA adsorption alone the long axis of the needlelike nanoparticles. (C) 2003 Elsevier Science Ltd. All rights reserved.
管管作品六首
(2003-10-01)
管管
A histogram-based moment-preserving clustering algorithm for video segmentation
(2003-10-01)
Lo, CC
;
Wang, SJ
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Video segmentation is the first step of creating video indices for a video retrieval system. A segmentation algorithm is used to identify shots from video data. In this paper, we propose a histogram-based moment-preserving (HBMP) clustering algorithm for segmenting video data. This algorithm is a hybrid of the shot change detection approach and the clustering approach. The computational results indicate that the proposed algorithm is both effective and efficient with respect to various types of video sequence. (C) 2003 Elsevier B.V. All rights reserved.
Three-frequency chaotic instability in soft-aperture Kerr-lens mode-locked laser around 1/3-degenerate cavity configuration
(2003-10-01)
Lin, JH
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
The quasi-periodic route to chaos from a three-frequency interaction was experimentally observed when the soft-aperture Kerr-lens mode-locked Ti:sapphire laser was operated in a cavity configuration that was around 1/3-degenerate, with non-zero group velocity dispersion. When the pump beam was smaller than the cold cavity beam, the laser oscillated among three frequencies, resulting in the modulation of phase-locked longitudinal modes. Increasing the pump power caused the nonlinear interaction of the three frequencies to induce a combination tones due to nonlinear gain and Kerr nonlinearity. Further secondary beating of these combinations tones at even higher pumping caused the system to become chaotic. Starting from the period-3 pulses in the 1/3-degenerate configuration, the quasi-periodic route to chaos was also observed when the configuration was tuned slightly away from degeneracy. (C) 2003 Elsevier B.V. All rights reserved.
Closure to "Passive earth pressure with critical state concept" by Yung-Show Fang, Ying-Chieh Ho, and Tsang-Jiang Chen
(2003-10-01)
Fang, YS
;
Ho, YC
;
Chen, TJ
;
土木工程學系
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Department of Civil Engineering
A case study in the design of BTO/CTO shop floor control system
(2003-10-01)
Chen, RS
;
Lu, KY
;
Yu, SC
;
Tzeng, HW
;
Chang, CC
Although computerized information systems are conventionally used to control production, applying a manual approach and improper logistical assignments typically reduces operating efficiency and increases customer service response time. Satisfying the requirements of remaining competitiveness in the current marketplace, such as offering build-to-order (BTO) or configuration-to-order (CTO) services is difficult. This study presents an integrated information system for use in shop floor controlling systems (SFCS) for kitting parts, producing goods, packing finished goods and distributing them, to enhance the performance of the BTO/CTO production system. Several information technologies and devices, such as barcode system, the electronic pick-to-light picking system, electronic Kanban (eKanban), and others are adopted to support the relevant logistics. A personal computer (PC) manufacturer is used to demonstrate the proposed system. The findings of the study reveal that the proposed information system can respond to the status of the production line in real time. This responsiveness can help the production controller to make a suitable decision and quickly meet the requirements of the BTO/CTO production system. (C) 2003 Elsevier Science B.V. All rights reserved.
Wide-sense nonblocking multicast Log(2) (N, m, p) networks
(2003-10-01)
Hwang, FK
;
Lin, BC
;
應用數學系
;
Department of Applied Mathematics
Recently, Tscha and Lee proposed a fixed-size window algorithm for the multicast Log(2) (N, 0, p) network and expressed a desire to see its extension to the Log(2) (N, m, p) network. Later, Kabacinski and Danilewiez generalized the fixed-size window to variable size to improve the results. In this paper, we further. extend the variable-size results from the Log(2) (N, 0, p) network to Log(2) (N, m, p). Note that this extension is difficult since each link in the channel graph of Log(2) (N, 0, p) has the same blocking effect, but not so in Log(2) (N, m, p). We also determine the optimal window size and optimal m.
Simulation analysis and experimental verification of UV-LIGA process for high-aspect-ratio Ni-Fe micro-mold insert
(2003-10-01)
Yeh, YM
;
Tu, GC
;
Fu, MN
;
材料科學與工程學系
;
Department of Materials Science and Engineering
UV (ultra violet)-LIGA (a German acronym for lithographic, gavanoformung, abformung), a low-cost microcomponent manufacturing technology for micro-electromechanical systems (MEMS), combines the UV patterning of thick photoresist layers with the molding of the resulting patterns by electroforming. It enables mass production of microcomponents using microinjection molding or hot embossing technology. This paper addresses the characteristics of the flow field and the mass transfer effect during micro-electroforming processes. A micro-electroforming experiment is conducted and a simulation is performed to determine optimal conditions for fine surface forming by micro-electroforming. Results show that a smaller diameter of a hole corresponds to poorer plating bath transfer. Plating bath can be replenished by increasing the rotation speed of the electrodes. However, mass transfer is still limited in holes with a high aspect ratio. The theoretical results of simulation analysis were verified by conducting practical electroforming experiments.
High reflectivity distributed Bragg reflectors for 1.55 mu m VCSELs using InP/airgap
(2003-10-01)
Tsai, JY
;
Lu, TC
;
Wang, SC
;
光電工程學系
;
Department of Photonics
A high reflecting InP/airgap distributed Bragg reflector (DBR) using InGaAs as sacrificial layers is demonstrated. The 3-pair InP/airgap DBR is formed by etching the InGaAs layers of the MOCVD grown InP/InGaAs structure using H2SO4 solution. A rigid and stable InP/airgap DBR with a peak reflectivity of 99.9% at 1.54 mum and a stopband width of about 200 nm is achieved. (C) 2003 Elsevier Ltd. All rights reserved.
Low-temperature-processed polycrystalline silicon thin-film transistors using a new two-step crystallization technique
(2003-10-01)
Fan, CL
;
Chen, MC
;
Chang, Y
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Low-temperature-processed (LTP) Polycrystalline silicon thin-film transistors (poly-Si TFTs) fabricated with a poly-Si film crystallized by a new two-step crystallization (NTSC) technique were investigated. The NTSC is characterized by the combination of excimer-laser-induced formation of nucleation centers and short-time low- temperature furnace annealing to create clear crystalline grains with very few in-grain defects. The LTP poly-Si TFTs fabricated with a NTSC poly-Si film not only exhibit better performance but also significantly shorten the crystallization time (about 6 h at 600degreesC) as compared to those fabricated using conventional solid phase crystallization (about 20 h or longer at 600degreesC).