Browsing by Issue Date, starting with "2006-09-12"

Now showing 1 - 20 of 62720

Blue-light generating femtosecond wavelength-tunable non-collinear optical parametric amplifier
(2006-09-12)
Pan
;
Ci-Ling
;
Huang
;
Jung Y.
;
Zhang
The present invention discloses a means of the generation of tunable femtosecond pulses from 380 nm to 465 nm near the degenerate point of a 405-nm pumped type-I BBO non-collinearly phase-matched optical parametric amplifier (NOPA). The tunable UV/blue radiation is obtained from sum frequency generation (SFG) between the OPA output and the residual fundamental beam at 810-nm and cascaded second harmonic generation (SHG) of OPA. With a pumping energy of 75 mJ at 405 nm, the optical conversion efficiency from the pump to the tunable SFG is more than 5% and the efficiency of SHG of the OPA is about 2%.
松尾芭蕉那隻青蛙
(2006-09-13)
管管
Gain flattened erbium-doped amplifier with 34 nm flat bandwidth
(2006-09-14)
Yeh, C. -H.
;
Lin, M. -C.
;
Chi, S.
;
光電工程學系
;
Department of Photonics
A gain-flattened two-stage erbium-based fibre amplifier module, structured by an erbium-doped waveguide amplifier and an erbium-doped fibre amplifier in serial, is proposed and demonstrated experimentally. In an operating range of 1528 to 1562 nm, all the gain is above 35 d13 and the noise figure is distributed from 5.5 to 6.7 dB, and +/- 1.1 dB maximum gain variation is retrieved at an input saturation power of -25 dBm. As a result, the proposed amplifier not only enhances gain value but possesses flatness in the operating region.
5.7 GHz GalnP/GaAs HBT sub-harmonic gilbert downconverter with octet-phase LO generator
(2006-09-14)
Wu, T. -H.
;
Meng, C.
;
Wu, T. -H.
;
電信工程研究所
;
Institute of Communications Engineering
A 5.7 GHz GaInP/GaAs heterojunction bipolar transistor (HBT) sub-harmonic Gilbert downconversion mixer with octet-phase LO generator is demonstrated. The conversion gain is 15 dB, IP1dB is - 13 dBm, IIP3 is 0 dBm, and IIP2 is 24 dBm when the LO power equals 3 dBm. The measured IF quadrature output waveforms indicate that the phase difference between the in-phase and quadrature-phase output channels is only 1.3 degrees.
Anti-control of chaos of single time-scale brushless DC motor
(2006-09-15)
Ge, Zheng-Ming
;
Chang, Ching-Ming
;
Chen, Yen-Sheng
;
機械工程學系
;
Department of Mechanical Engineering
Anti-control of chaos of single time-scale brushless DC motors is studied in this paper. In order to analyse a variety of periodic and chaotic phenomena, we employ several numerical techniques such as phase portraits, bifurcation diagrams and Lyapunov exponents. Anti-control of chaos can be achieved by adding an external constant term or an external periodic term.
Angular and energy dependences of the surface excitation parameter for electrons crossing a solid surface
(2006-09-15)
Kwei, C. M.
;
Li, Y. C.
;
Tung, C. J.
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
When fast electrons cross a solid surface, surface plasmons may be generated. Surface plasmon excitations induced by electrons moving in the vacuum are generally characterized by the surface excitation parameter. This parameter was calculated for 200-1000 eV electrons crossing the surfaces of An, Cu, Ag, Fe, Si, Ni, Pd, MgO and SiO, with various crossing angles. Such calculations were performed based on the dielectric response theory for both incident (from vacuum to solid) and escaping (from solid to vacuum) electrons. Calculated results showed that the surface excitation parameter increased with crossing angle but decreased with electron energy. This was due to the longer time for electron-surface interaction by glancing incident or escaping electrons and by slow moving electrons. The results were fitted very well to a simple formula, i.e. P-s = aE(-b)/(cosx)(c), where P, is the surface excitation parameter, E is the electron energy, alpha is the angle between the electron trajectory and the surface normal, and a, b and c are material dependent constants. (c) 2006 Elsevier B.V. All rights reserved.
Build-up of supercontinuum in heated and unheated photonic crystal fibers using a chirped femtosecond laser
(2006-09-15)
Lin, Ja-Hon
;
Hsu, Chih-Chang
;
Hsieh, Wen-Feng
;
Lin, Kuel-Huei
;
光電工程學系
The build-up of supercontinuum in a photonic crystal fiber (PCF) has been investigated experimentally as a function of pump power using chirped 100-fs pulses from a Ti:sapphire laser. As compared with the PCF at room temperature, a new blue-shifted spectral component is observed in the initial steps of supercontinuum (SC) generation when the central part of PCF is heated to 120 degrees C by a hot plate. In addition, the slope efficiency of SG is slightly improved with the slightly extension of supercontinuum spectrum in blue edge at high pump powers. The change in dispersion property as well as the effective cascading of nonlinear photonic crystal fibers for heated PCF would be the main attributions. (c) 2006 Elsevier B.V. All rights reserved.
Self-assembled In0.22Ga0.78As quantum dots grown on metamorphic GaAs/Ge/SixGe1-x/Si substrate
(2006-09-15)
Hsieh, Y. C.
;
Chang, E. Y.
;
Luo, G. L.
;
Chen, S. H.
;
Biswas, Dhrubes
Self-assembled In0.22Ga0.78As quantum dots (QDs) grown on Si substrate with Ge/SiGe as buffer layer grown by metal organic vapor phase epitaxy were investigated. Transmission electron microscopy and atomic force microscopy images were used to observe the size and space distribution of the In0.22Ga0.78As QDs grown on the GaAs/Ge/GeSi/Si layer structure. The influence of the growth temperature on the QDs size and density distribution was investigated. For QDs grown at 450 degrees C, the density of the In0.22Ga0.78As dots was estimated to be 1x10(11) cm(-2) and the In0.22Ga0.78As QDs thickness was 5 ML (monolayer) thick. (c) 2006 American Institute of Physics.
X-ray initiated molecular photochemistry of Cl-containing adsorbates on a Si(100) surface using synchrotron radiation
(2006-09-15)
Chen, J. M.
;
Lu, K. T.
;
Lee, J. M.
;
Haw, S. C.
;
電子物理學系
X-ray initiated molecular photochemistry for SiCl(4) and CCl(4) adsorbed on Si(100) at similar to 90 K following C1 2p core-level excitation is investigated by photon stimulated ion desorption and ion kinetic energy distribution measurements. The Cl 2p -> 8a(1)*, excitation of solid SiCl(4) induces the significant enhancement (similar to 900%) of the Cl(+) yield, while the Cl 2p -> 7a(1)* excitation of condensed CCl(4) leads to a moderate enhancement (similar to 500%) of the Cl(+) yield. The enhancement of Cl(+) yield at the specific core-excited states is strongly correlated to the ion escaped energy. Upon X-ray exposure for CCl(4) adsorbed on Si(100) (20-L exposure), the Cl(+) yields at 7a(1)* resonances decrease and new structures at higher photon energies are observed. Cl+ yields at these new resonances are significantly enhanced compared to those at other resonances. These changes are the results of desorption and surface reaction of the CCl(4)-Si surface complex due to X-ray irradiation. We have demonstrated that state-specific enhancement of ion desorption can be successfully applied to characterize the reaction dynamics of adsorbates adsorbed on surfaces by X-ray irradiation. (c) 2006 Elsevier B.V. All rights reserved.
Electroluminescence from a conjugated polymer grafted with CdSe/ZnS: High brightness and improved efficiency
(2006-09-15)
Chen, Kuei-Bai
;
Chen, Ming-Hwey
;
Yang, Sheng-Hsiung
;
Hsieh, Chao-Hsiang
;
Hsu, Chain-Shu
A new series of sulfide-substituted poly(1,4-phenylene vinylene) derivatives (S1PPV-S3PPV) with different composition ratios were successfully synthesized,via the Gilch route. The CdSe/ZnS were grafted to the sulfur atoms by ligand exchange reaction. The grafted CdSe/ZnS contents were determined from TGA analysis to be from 4.6 to 37.8%. A new peak at 1151 cm(-1) formed in FT-IR after ligand exchange, which is attributed to the force formation between sulfur and CdSe. The GPC results show that the molecular weights of final polymers became higher after ligand exchange. Thin films of obtained polymers emitted bright green and yellow light with the max emission peak located from 546 to 556 nm. Double-layer LEDs with an ITO/PEDOT/polymer/Ca/Al configuration were fabricated to evaluate the potential use of these polymers. The turn-on voltages of the devices were about 4-5 V As the CdSe/ZnS content increased in grafted polymers, the device performance was significantly enhanced as compared to pristine polymers. In the case of S3PPV, the double-layer device showed a maximum luminance of 6073 cd/m(2) with a current yield of 0.82 cd/A. The maximum luminance and current yield was enhanced to 13,390 cd/m(2) and 2.25 cd/A by grafting CdSe/ZnS onto polymers. (c) 2006 Wiley Periodicals, Inc.
去除硫化物與資源再生之系統
(2006-09-16)
曾慶平
;
鍾竺均
本發明係為一去除硫化物與資源再生之系統，其藉由化學吸收法將硫化氫氣體吸收與轉化，使轉化之產物於沉澱槽裝置進行分離與回收，並利用生物氧化法將化學吸附劑再生，並將再生後之化學吸附劑迴流至化學除硫槽裝置，繼續與入流之硫化氫氣體進行反應，使系統成為一吸收-氧化-分離-回收-再生之生化密閉循環系統。
音效處理裝置及其處理方法
(2006-09-16)
白明憲
;
白淦元
;
周中權
本發明提出一種音效處理裝置及其處理方法，藉由在一裝置內整合多種特殊音效的處理，並且可以進行雜音效除及斷點消除，使得聲音品質提高，且增進娛樂效果，且因整合於一裝置，可即時播放及操作，可達到較低的運算量。
Evaluating IT/IS investments: A fuzzy multi-criteria decision model approach
(2006-09-16)
Chou, Tzy-Yuan
;
Chou, Seng-cho T.
;
Tzeng, Gwo-Hshiung
;
科技管理研究所
;
Institute of Management of Technology
IT/IS represents a substantial financial investment for many organizations. Whether or not to invest in new IT/IS is, therefore, a difficult decision. Simply considering human resource cost saving criteria is not enough, especially when a corporation has had many information systems. What kind of criteria should we consider when we evaluate IT/IS? How can a new IT/IS project be evaluated in an easy, cost-effective, and collective manner? We need a tool that will help decision-makers evaluate potential new investment projects. Apart from evaluating the new project per se, its compatibility and ability to integrate with an existing IT portfolio must also be considered. Hence, we propose a new approach based on the fuzzy multi-criteria decision model (FMCDM), featuring a 2-stage evaluation process with 26 criteria for IT/IS investment. All stakeholders in a corporation can decide the relative weights they give to the criteria when they evaluate a new IT/IS project by using linguistic values. Experts can also use linguistic values to evaluate all candidates easily. Only an Excel worksheet is needed to obtain an evaluation result. It is cost-effective and efficient. We conduct a case study to show how this model can be used and discuss the results. (c) 2005 Elsevier B.V. All rights reserved.
Emission characteristics of optically pumped GaN-based vertical-cavity surface-emitting lasers
(2006-09-18)
Chu, Jung-Tang
;
Lu, Tien-Chang
;
You, Min
;
Su, Bor-Jye
;
Kao, Chih-Chiang
The laser emission characteristics of a GaN-based vertical-cavity surface-emitting laser with two dielectric distributed Bragg reflectors were investigated under optically pumped operation at room temperature. The laser emitted wavelength at 415.9 nm with an emission linewidth of 0.25 nm and threshold pumping energy of 270 nJ. The laser has a high characteristic temperature of about 278 K and high spontaneous emission coupling factor of 10(-2). The laser emission showed single and multiple spot emission patterns with spectral and spatial variations under different pumping conditions. (c) 2006 American Institute of Physics.
Structure of HfO2 films epitaxially grown on GaAs(001)
(2006-09-18)
Hsu, C. -H.
;
Chang, P.
;
Lee, W. C.
;
Yang, Z. K.
;
Lee, Y. J.
High-quality HfO2 films of technologically important thickness ranging from 1.8 to 17 nm have been grown epitaxially on GaAs (001) by molecular beam epitaxy. Thorough structural and morphological investigations were carried out by x-ray scattering and high-resolution transmission electron microscopy. The films exhibit an atomically sharp interface with the substrate and are of a monoclinic phase with predominant (001)-plane epitaxy between the HfO2 films and GaAs, in spite of a large lattice mismatch of > 8.5%.
Highly efficient and stable sky blue organic light-emitting devices
(2006-09-18)
Lin, Mei-Fang
;
Wang, Lei
;
Wong, Wai-Kwok
;
Cheah, Kwok-Wai
;
Tam, Hoi-Lam
A highly efficient and stable sky blue organic light-emitting device doped with a sky blue dopant BUBD-1 has been fabricated, achieving an electroluminescence efficiency of 13.2 cd/A and 6.1 lm/W at 20 mA/cm(2) and 6.7 V, with Commission Internationale del'Eclairage coordinates of (0.16, 0.30) and a half-decay lifetime of 1815 h at an initial brightness of 2640 cd/m(2). This performance is one of the best blue devices ever reported without using hole blocking layer or any p or n dopant in hole or electron transport layer. (c) 2006 American Institute of Physics.
Method for fabrication of polycrystallin silicon thin film transistors
(2006-09-19)
Yeh
;
Ching-Fa
;
Chen
;
Tien-Fu
;
Lou
A method for fabricating polycrystalline silicon film transistors, which includes a polysilicon spacer capping onto a sidewall of an active layer in the thin film transistors by an isotropic dry etching of the silicon film. This method suppresses the shrinkage of the active layer during recrystallization by the laser. Large grains are formed in the channel after recrystallization utilizing a high-energy continuous wavelength laser or an excimer laser annealing the active layer. This process does not require an additional mask. Uniform arrangement of grain boundaries and large grain sizes promotes uniformity of performance of the device, which is important in the fields of low temperature polycrystalline silicon thin film transistors (LTPS-TFTs).
Syntheses and specific interactions of poly (hydroxyethyl methacrylate-b-vinyl pyrrolidone) diblock copolymers and comparisons with their corresponding miscible blend systems
(2006-09-20)
Huang, Chih-Feng
;
Kuo, Shiao-Wei
;
Lin, Fang-Ju
;
Wang, Chih-Feng
;
Hung, Chen-Jui
Combination of atom transfer radical and conventional free radical polymerizations has been successfully used to prepare poly(hydroxyethyl methacrylate-b-vinyl pyrrolidone) (PHEMA-b-PVP) copolymers with controlled molecular weight and low polydispersity (< 1.4). The thermal behavior and specific interaction of PHEMA-b-PVP diblock copolymers and their corresponding PHEMA/PVP blends were characterized. The result shows that glass transition temperatures of diblock copolymers analysed by differential scanning calorimetry (DSC) are higher than those of the blends. Infrared and solid-state NMR spectroscopic analyses show that hydrogen-bonding interaction of hydroxyl-carbonyl groups of diblock copolymers was also greater than that of the blends. Measurement of the proton spin-lattice relaxation time in the rotating frame, (T-1P(H)), reveals that all diblock copolymers and blends possess one composition-dependent T H, indicating that both diblock copolymers and blends are homogeneous, which is consistent with the DSC analysis. (c) 2006 Elsevier Ltd. All rights reserved.
製造奈米線的方法和儀器
(2006-09-21)
朝春光
;
郭金國
;
陳建仲
;
陳蓉萱
一種製造奈米線的方法，是以一液壓使熔融材料進入模板之奈米通道，再凝固熔融材料，以形成數個奈米線。本發明可製作各種成份之合金奈米線且對環境污染性低。再者，本發明所製作出的合金奈米線之純度高、缺陷少、製程簡單且效率高。另外，本發明之方法亦適用於製作高分子、陶瓷及複合材料等奈米線。
感應地層移動之光纖光柵雙軸承式偏斜儀
(2006-09-21)
黃安斌
;
何彥德
本發明提供一種用於感應地層移動之監測儀，包括：感測元件是由兩端剛性鋁片加上中間一節撓性軟管所組成，且利用應變監測管之原理與節理式機構之設計而達到訊號放大之效應。其中，在節理間安裝兩個雙軸承，其中一個軸承與監測管方向同軸(滑動軸承)，在於解除感測器受監測管軸向力(包括重力與摩擦力)對感測器之影響，另一個軸承與監測管方向垂直(轉動軸承)，在於限制偏斜儀節理之間只能以橫向軸承為中心旋轉而增加結果分析之可靠度。使用此一設計可以獲得穩定而具有高度重複性之讀數，以便使用雙軸承式偏斜儀做定量之監測與結果分析。