Browsing by Issue Date, starting with "2006-04-04"

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Fiber-optic tunable filter and intensity modulater
(2006-04-04)
Chen
;
Nan-Kuang
;
Chi
;
Sien
;
Tseng
A fiber-optic tunable filter and an intensity modulator respectively includes: a fiber having a polished surface and an evanescent-field; and a photonic crystal having plural cavities and a filler filled therein and attached to the polished surface, wherein the plural cavities and the filler decide a photonic band-gap of the photonic crystal and the photonic band-gap is adjusted to reflect a light with a specific wavelength through the evanescent interaction with the photonic crystal material. Based on the fiber side-polishing technique, all kinds of fiber active and passive devices are able to be manufactured easily, especially for a high speed intensity modulator using an EO (Electro-Optic) polymer as the filler.
藍
(2006-04-08)
管管
Multipass acoustically open photoacoustic detector for trace gas measurements
(2006-04-10)
Miklos, A
;
Pei, SC
;
Kung, AH
;
光電工程學系
;
Department of Photonics
What we believe to be a novel multipass, acoustically open photoacoustic detector designed for fast-response, high-sensitivity detection of trace gases and pollutants in the atmosphere is demonstrated. The acoustic pulses generated by the absorption of the light pulses of a tunable optical parametric oscillator by target molecules are detected by an ultrasonic sensor at 40 kHz. The photoacoustic signal is enhanced by an optical multipass arrangement and by concentration of the acoustic energy to the surface of the ultrasonic sensor. The detection sensitivity, estimated from CO2 measurements around a 2 mu m wavelength, is similar to 3.3 x 10(-9) W cm(-1). (c) 2006 Optical Society of America.
Star-like fluorene based polyamines: non-conjugated building blocks for light-harvesting materials
(2006-04-10)
Thomas, KRJ
;
Lin, JT
;
Tsai, CM
;
Lin, HC
;
材料科學與工程學系
We report herein a series of novel tetramines (2-6) built using the fluorene core. The design features a diamine conjugated by a fluorene core and two non-conjugated triarylamines dangling through the bridge methine moiety. These polyamines are amorphous in nature and display moderate emission properties that are either dependent on the nature of the arylamine segments or reminescent of the fluorene backbone. The phenyl, naphthyl, fluorenyl and carbazolyl amine based materials are blue emissive while the pyrenylamine based compound emits yellow-green color. We demonstrate a possibility of using blue-emitting fluorene derivatives (2 and 4) blended with poly(N-vinylcarbazole) (PVK) to fabricate organic light emitting diodes (OLEDs). Emissions in the EL devices purely originated from the fluorene derivatives alone (blue) are contaminated with those of complex species (electromer/electroplex) formed by intermolecular interactions. (c) 2006 Elsevier Ltd. All rights reserved.
Parallel synthesis of amino bis-benzimidazoles by multistep microwave irradiation
(2006-04-10)
Wu, CH
;
Sun, CM
;
應用化學系
;
Department of Applied Chemistry
A multistep liquid phase synthesis of specifically functionalized bis-benzimidazoles is presented by the application of single-mode microwave irradiation technique. The sustained solubilizing power and stability of the PEG-ester derived from the commercially available 4-fluoro-3-nitrobenzoic acid has been successfully carried through 10 steps involving iPSO-SNAr reaction, neutral reduction and acid cyclization. All the steps in this synthetic sequence were assisted by microwave (MW) irradiation. The polymer support was cleaved to release the final head to tail bisbenzimidazoles in an efficient process. (c) 2006 Elsevier Ltd. All rights reserved.
Optical switching properties of VO2 films driven by using WDM-aligned lasers
(2006-04-10)
Tsai, KY
;
Wu, FH
;
Shieh, HPD
;
Chin, TS
;
光電工程學系
Vanadium dioxide (VO2) film had been demonstrated a high speed IR shutter driven by total optical modulation. However, it usually required a higher power heating laser of high power and precise optical systems to cover the probe beam on the sample with a heating beam of larger area. A new optical system, simply composed of wavelength division multiplexing (WDM), fiber lens or convex lens system, and a glass sheet with VO2 thin film on it, was easily assembled to utilize VO2 film as an IR shutter, implying the possibility to highly miniaturize the VO2-based optical shutter. A permanent low-transmittance (PLT) region forms on the film within the probe beam, resulting in a decrease in average power of the probe beam. Another ring-type switching area (switching ring) forms around the PLT region, resulting in the transmittance switching of the probe beam synchronously with the heating signal. VO2 films can be switched with the highest rate of a continuous square heating signal of 3 mW at 120 kHz. A heating pulse of 0.7ns and 13mW can be used to stimulate an IR pulse with fiber lens. (c) 2005 Elsevier B.V. All rights reserved.
Fast motion estimation using N-queen pixel decimation
(2006-04-11)
Wang
;
Chung-Neng
;
Yang
;
Shin-Wei
;
Liu
The present invention proposes a fast motion estimation using N-queen pixel decimation, whereby after a reference block and a block to be processed are selected in a video sequence, an N×N queens pattern is used for pixel decimation to perform block match, thereby obtaining a good enough block difference value. The present invention combines pixel decimation with fast motion estimation for search points reduction to achieve the object of simplifying computational complexity of motion estimation. Therefore, the present invention can sieve out sufficiently representative pixels and will not increase extra computational complexity.
Miniaturized microwave integrated circuit using complementary conducting surfaces
(2006-04-11)
Tzuang
;
Ching-kuang
;
Chen
;
Chih-chiang
The invention discloses a two-dimensional array waveguide structure implemented with multi-layer process or monolithic integrated circuit process. The structure includes a first metal layer, a second metal layer and a dielectric layer. The dielectric layer lain between the first and the second metal layer is for isolating the first metal layer from the second metal layer. The first metal layer and the second metal layer respectively formed from a plurality of first unit cells and second unit cells arranged in rows and columns create the two-dimensional array waveguide structure. The first metal layer consists of a main body and a plurality of connecting arms, whereas the second metal layer consists of a metal wire loop. The second metal layer is located below the first metal layer, and each second unit cell corresponds to each first unit cell in a one-on-one manner to further build a complete unit cell. While the main body of each unit cell corresponds to an inductance element, the connecting arms of each unit cell linking the adjacent unit cells correspond to a capacitance element; therefore, a two-dimensional L-C array is formed.
Fast wavelength-tunable laser system using Fabry-Perot laser diode
(2006-04-11)
Chi
;
Sien
;
Lee
;
Chien-Chung
;
Yeh
The invention relates to a laser system using a multi-longitudinal-mode Fabry-Perot laser diode as an inter-injection light source and a gain cavity formed by other laser diodes of such type so as to achieve the function of fast wavelength switching, so that it is possible to achieve repetitively fast switching of wavelength by varying and controlling the bias voltage of maximum optical gain in said inter-injection type multi-longitudinal-mode Fabry-Perot laser diode so as to achieve three different wavelengths with tuning range of 3.5 nm for a side-mode suppression ratio (SMSR) greater than 19 dB and a response time of wavelength switching in the order of nanosecond.
On-line preconcentration and determination of ketamine and norketamine by micellar electrokinetic chromatography - Complementary method to gas chromatography/mass spectrometry
(2006-04-14)
Jen, HP
;
Tsai, YC
;
Su, HL
;
Hsieh, YZ
;
應用化學系
We have investigated a rapid, simple, and highly efficient on-line preconcentration method using in micellar electrokinetic chromatography (MEKC) for the analysis of abused drugs. Ketamine is an anesthetic that has been abused as a hallucinogen. We applied the sample sweeping technique first to ketamine and its major metabolite, norketamine, and separated the analytes with MEKC. Several of the sweeping MEKC parameters to effect successful separations, such as the concentration of sodium dodecyl sulfate (SIDS), the injection time, and the applied voltage were optimized. The improvements in the number of theoretical plates under the different separation conditions are presented clearly in a three-dimensional representation. The limits of detection were 2.8, 3.4, and 3.3 ng/mL for ketamine, norketamine, and ketamine-D-4, respectively. The enrichment factor for each compound was within the range of 540-800. Experimental results are in agreement with those of analysis conducted by gas chromatography/mass spectroscopy (GC/MS). Therefore, we believe that sweeping, combined with MEKC, represents a suitable complementary method to GC/MS for use in clinical and forensic analyses of ketamine and norketamine. (c) 2005 Elsevier B.V. All rights reserved.
Fabrication of microfluidic devices using dry film photoresist for microchip capillary electrophoresis
(2006-04-14)
Tsai, YC
;
Jen, HP
;
Lin, KW
;
Hsieh, YZ
;
應用化學系
An inexpensive, disposable microfluidic device was fabricated from a dry film photoresist using a combination of photolithographic and hot roll lamination techniques. A microfluidic flow pattern was prefabricated in a dry film photoresist tape using traditional photolithographic methods. This tape became bonded to a poly(methyl methacrylate) (PMMA) sheet with prepouched holes when passed through a hot roll laminator. A copper working electrode and platinum decoupler was readily incorporated within this microchip. The integrated microchip device was then fixed in a laboratory-built Plexiglas holder prior to its use in microchip capillary electrophoresis. The performance of this device with amperometric detection for the separation of dopamine and catechol was examined. The separation was complete within 50 s at an applied potential of 200 V/cm. The relative standard deviations (RSD) of analyte migration times were less than 0.71%, and the theoretical plate numbers for dopamine and catechol were 3.2 x 10(4) and 4.1 x 10(4), respectively, based on a 65 min separation channel. (c) 2005 Elsevier B.V. All rights reserved.
Current detection of vortex motion in patterned S-shape wires with constrictions
(2006-04-15)
Chen, YC
;
Yao, YD
;
Lee, SF
;
Lin, YA
;
Chen, DC
The current-driven effect on the vortex domain wall in a series-connected permalloy S-shape patterns was investigated. When a domain wall is initially formed in the wire section, in contrast to the ac result, applying a low dc current (J similar to 10(5) A/cm(2)) will break the degeneracy of the switching energy in different connected sections. Moreover, three kinds of effects on vortex states are observed by applying a high dc current (J similar to 10(7) A/cm(2)). The current applied slightly below the original switching field will drive vortices to constrictions while the current applied far below the original switching field will only perturb the vortex to another stable state. At the fields slightly over the original switching field, the domain walls are initially trapped at constrictions, injecting current will cause both the depinning and deformation of vortices. (C) 2006 American Institute of Physics.
Effects of an Os layer on the magnetic properties of CoFe/IrMn
(2006-04-15)
Peng, TY
;
Lo, CK
;
Chen, SY
;
Yao, YD
;
材料科學與工程學系
The uses of Os as an antidiffusion and buffer layer in IrMn exchange coupled CoFe film were investigated. For the purpose of antidiffusion, the inserted Os layer showed a distinct improvement of S>0.9, with H-C slightly increasing by 1.6 times for the CoFe/Os/MnOs multilayer after 400 degrees C annealing, even though the Os thickness was as thin as 0.3 nm. Furthermore, with a 0.3 nm Os barrier, the 350 degrees C annealed CoFe/Os/IrMn/CoFe showed almost the same magnetic behavior as the as-deposited state, while the H-ex of the upper part of the CoFe/Os/IrMn changed from 100 to 190 Oe. In addition, as a buffer layer, the Os buffer layer could enhance the diffraction peak intensities of IrMn(111)/Os(002) and CoFe (111), and the H-ex of CoFe/IrMn was proportional to the Os thickness. A 120 Oe of H-ex was achieved by using an 11 nm Os buffer layer in a CoFe 10 nm/IrMn 15 nm bottom type film. These results show that Os has the potential to be an antidiffusion and buffer layer in a magnetic multilayer. (C) 2006 American Institute of Physics.
Anisotropy transition of Co in IrMn/Co/FeOx/Co by field cooling
(2006-04-15)
Shen, CT
;
Lai, CH
;
Huang, PH
;
Hsu, SY
;
Chung, TY
The temperature dependence of Co anisotropy on a nano-FeOx layer was studied in the structure of IrMn/Co (FM1)/FeOx/Co (FM2). An anisotropy transition of the FM2 was observed from a combination of uniaxial and unidirectional anisotropies at room temperature (RT) to unidirectional anisotropy at temperature below 80 K through field cooling process. Various ferromagnetic (FM) and antiferromagnetic (AFM) components existing in the FeOx layer were attributable to the observed anisotropy of FM2. AFM domains with T-N higher than room temperature were responsible for the observed uniaxial anisotropy at RT and AFM domains with T-N of 80 K were accountable for the anisotropy transition, below which the unidirectional anisotropy became dominant. In addition, the direction of the shifted loop could be determined by the cooling field direction. (C) 2006 American Institute of Physics.
Effect of bisphenol A on the miscibility, phase morphology, and specific interaction in immiscible biodegradable poly(epsilon-caprolactone)/poly(L- lactide) blends
(2006-04-15)
Kuo, SW
;
Huang, CF
;
Tung, YC
;
Chang, FC
;
應用化學系
We have investigated the enhancement in miscibility, upon addition of bisphenol A (BPA) of immiscible binary biodegradable blends of poly(epsilon-caprolactone) (PCL) and poly(L-lactide) (PLLA). That BPA is miscible with both PCL and PLLA was proven by the single value of T-g observed by differential scanning calorimetry (DSC) analyses over the entire range of compositions. At various compositions and temperatures, Fourier transform infrared spectroscopy confirmed that intermolecular hydrogen bonding existed between the hydroxyl group of BPA and the carbonyl groups of PCL and PLLA. The addition of BPA enhances the miscibility of the immiscible PCL/PLLA binary blend and transforms it into a miscible blend at room temperature when a sufficient quantity of the BPA is present. In addition, optical microscopy (OM) measurements of the phase morphologies of ternary BPA/PCL/ PLLA blends at different temperatures indicated an upper critical solution temperature (UCST) phase diagram, since the Delta K effect became smaller at higher temperature (200 degrees C) than at room temperature. An analysis of infrared spectra recorded at different temperatures correlated well with the OM analyses. (c) 2006 Wiley Periodicals, Inc.
Development of micromagnetic bearing motors with suppressed magnetic coupling effect for small form factor optical drives
(2006-04-15)
Wang, CC
;
Yao, YD
;
Wang, SJ
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The aim of this paper was to design a micromagnetic bearing (MMB) motor for small form factor optical drives. A MMB motor was developed with inner and outer magnetic-ring stack structure of high permeability. These rings were arranged on the shaft above the permanent magnet of the rotor and the stator. The magnetic force between the MMB, the permanent magnet, and the stator induced the magnetic coupling effect that generated the demon friction torque loss. However, the loss was controlled well under 1.93x10(-4) N m by the proposed approach, so that the good stable system was achieved. After suppressing the loss caused by the magnetic coupling effect, the shaft can be rotated without any frictional contacts in radial direction, the running current was around 0.18 A, and the maximum speed was around 1850 rpm. It shows that the MMB demonstrates the lower friction torque loss in comparison with the conventional microball bearing (MBB). Moreover, the radial vibration of our device is 21% lower than the conventional MBB type. To verify the performance of the provided system, both the computer simulation and the experiment were performed. (C) 2006 American Institute of Physics.
Voltage-controlled liquid-crystal terahertz phase shifter and quarter-wave plate
(2006-04-15)
Hsieh, CF
;
Pan, RP
;
Tang, TT
;
Chen, HL
;
Pan, CL
Phase shift exceeding pi/2 at 1 THz is demonstrated by using electrically controlled birefringence in a homeotropically aligned nematic liquid crystal (E7) cell, 570 mu m in thickness. The driving voltage required for a phase shift of 90 degrees is 125 V (rms). We demonstrate that the phase shifter works as an electrically switchable quarter-wave plate at I THz. The device can also be used as an electrically tuned phase compensator around the quarter-wave point near 1 THz. (c) 2006 Optical Society of America.
A novel algorithm for dynamic factor analysis
(2006-04-15)
Huang, JJ
;
Tzeng, GH
;
Ong, CS
;
科技管理研究所
;
Institute of Management of Technology
In this paper, a dynamic factor model is proposed to extract the dynamic factors from time series data. In order to deal with the problem of scaling, the cross-correlation matrices (CCM) are first employed to cluster the time series data. Then, the dynamic factors are extracted using the revised independent component analysis (ICA). In addition, a numerical study is used to demonstrate the proposed method. On the basis of the simulated results, we can conclude that the proposed method can really extract the effective dynamic factors. (c) 2005 Elsevier Inc. All rights reserved.
Analysis of diffusive interface resistance for measurements with perpendicular current in Fe/Nb multilayers
(2006-04-15)
Huang, S. Y.
;
Lee, S. F.
;
Yu, C. Y.
;
Hsu, S. Y.
;
Yao, Y. D.
In this study, we investigated the electron transport properties of interface between a ferromagnet and a superconductor with flowing current perpendicular to plan (CPP) at 4.2 K in Fe/Nb multilayers. The CPP resistance increased linearly with layer thickness and with bilayer number. We extracted the unit area resistance value of one pair of interface for superconducting and normal Fe/Nb by using a series resistor model. Hence, we can quantitatively analyze the interface resistance between Fe and Nb in the diffusive regime. (C) 2006 American Institute of Physics.
Vortex domain wall depinning by polarized current in submicron half-ring wires
(2006-04-15)
Chen, YS
;
Cheng, KW
;
Yu, C
;
Lee, SF
;
Chen, DC
Domain wall pinning force in the junctions (corners), with different shapes of square, semicircle, or triangle, of half-ring in-series wires is considered to study the current injection induced wall movements. This geometry has less thermal activation at the region of domain wall nucleation in contrast to notch structures. The wires with square corners have the largest domain pinning force to resist polarized current-induced magnetization reversal, judging from the largest slope in the current-field dependence (Delta I/Delta H=0.274). (C) 2006 American Institute of Physics.