Browsing by Issue Date, starting with "2009-10-26"

Now showing 1 - 20 of 49561

Temperature dependent gain characteristics in GaN-based vertical-cavity surface-emitting lasers
(2009-10-26)
Lu, Tien-Chang
;
Cheng, Bo-Siao
;
Liu, Mei-Chung
;
光電工程學系
;
Department of Photonics
Temperature dependent gain characteristics and linewidth enhancement factor (alpha-factor) of vertical-cavity surface-emitting lasers with InGaN/GaN multiple quantum wells were studied by measuring the photoluminescence spectra below the threshold condition and analyzed by using the Hakki-Paoli method. The optical gain and differential gain showed a more rapid increase as a function of the injected carriers as temperature decreased. The alpha-factor for the lasing mode was estimated as 2.8 at room temperature and decreased to a value as low as 0.6 at 80 K. (C) 2009 Optical Society of America
A continuously tunable and filterless optical millimeter-wave generation via frequency octupling
(2009-10-26)
Lin, Chun-Ting
;
Shih, Po-Tsung
;
Jiang, Wen-Jr
;
Chen, Jason (Jyehong)
;
Peng, Peng-Chun
This work proposes a cost-effective, continuously tunable and filterless optical millimeter-wave (MMW) signal generation employing frequency octupling. Optical MMW signals with 30-dB undesired sideband suppression ratios can be obtained. Since no optical filtering is required, the proposed system can be readily implemented in wavelength-division-multiplexing (WDM) systems. V-band 60-GHz and W-band 80-GHz optical MMW signals are experimentally demonstrated. Because of the high undesired sideband suppression ratio, 60-GHz waveform with 50% duty cycle is observed. The single-sideband (SSB) phase noise of the generated 60-GHz signal is -73 dBc/Hz at 10 kHz. The proposed system is a viable solution for the future ultra-high frequency MMW applications up to 320 GHz using the external modulator with a limited bandwidth of 40 GHz. (C) 2009 Optical Society of America
Full duplex 60-GHz RoF link employing tandem single sideband modulation scheme and high spectral efficiency modulation format
(2009-10-26)
Shih, Po-Tsung
;
Lin, Chun-Ting
;
Jiang, Wen-Jr
;
Chen, Yu-Hung
;
Chen, Jason (Jyehong)
This study proposes a full duplex 60-GHz band radio-over-fiber (RoF) link using a modified tandem single sideband (TSSB) modulation scheme with frequency doubling. Based on the modified TSSB modulation scheme, no dispersion induced fading is observed; high spectral efficiency vector signal can be utilized; and wavelength reuse can also be achieved. Both single carrier 8-QAM and QPSK-OFDM signals for down-link transmissions are experimentally demonstrated. After transmission of 50-km SSMF, no significant receiver power penalties are observed. Wavelength reuses with 1.25-Gb/s OOK using a reflective semiconductor optical amplifier (RSOA) for up-link transmission are also demonstrated. After transmission of 50-km SSMF, no significant receiver power penalties are also observed. (c) 2009 Optical Society of America
Heterogeneity-projection hard-decision interpolation method for color reproduction
(2009-10-27)
Tsai
;
Chi-Yi
;
Song
;
Kai-Tai
The present invention discloses a heterogeneity-projection hard-decision interpolation method for color reproduction, which utilizes a heterogeneity-projection method to determine the optimal edge direction and then utilizes a hard-decision rule to determine the optimal interpolation direction and obtain the information of the green color elements. The high-frequency information of the plane of the green color elements is incorporated into the processing of the planes of the red color elements and the blue color elements to reduce the restoration errors of the red and blue color elements. Therefore, the present invention can decrease the interpolation-direction errors and achieve a higher PSNR and a better visual effect.
Real-time observation of dynamic coupling between the stretching and bending modes in a polythiophene
(2009-10-28)
Du, Juan
;
Kobayashi, Takayoshi
;
電子物理學系
;
Department of Electrophysics
By real-time vibrational spectroscopy using 6.3 fs pulses, both instantaneous frequency and amplitude modulated with frequency of 120-130 cm(-1) were observed for the C-C stretching mode with the central frequency of 1343 cm(-1) in a poly-(substituted thiophene). This provided the evidence that a stretching mode dynamically couples with another stretching mode mediated by a low-frequency bending mode. Instantaneous bond-order changed during the bending motion due to the change in the distribution of pi-electrons. The coupling between the stretching and bending modes was found to be maintained for longer than 1200 fs after the start of the coherent molecular vibration. (C) 2009 Elsevier B.V. All rights reserved.
四種愛
(2009-10-28)
楊蔚齡
;
開放教育推動中心
;
Open Education Office
課程日期： 2009年10月28日(三) 演講人：楊蔚齡小姐內容摘要：楊蔚齡秘書長以一小段影片開頭，敘述一位失去雙臂女士如何單用雙腳活出生命的色彩，他以四個層面來探討愛，包含有所求、無所求、本能和超越的愛，其中前三個是大家最常感受到的，最後一種可能是許多人未曾經歷過，或者是我們可能有所感受，但卻沒有表現出來。內容：影音實況影音(*.flv檔)
Vertical Transmission Structure
(2009-10-29)
Chang, Edward Yi
;
Wu, Wei-Cheng
;
Hwang, Ruey-Bing
;
Hsu, Li-Han
A vertical transmission structure for high frequency transmission lines includes a conductive axial core and a conductive structure surrounding the conductive axial core. The vertical transmission structure is applied to a high-frequency flip chip package for reducing the possibility of underfill from coming in contact with the conductive axial core.
Automatized Parametrization of SCC-DFTB Repulsive Potentials: Application to Hydrocarbons
(2009-10-29)
Gaus, Michael
;
Chou, Chien-Pin
;
Witek, Henryk
;
Elstner, Marcus
;
應用化學系
In this work, we derive and test a new automatized strategy to construct repulsive potentials for the self-consistent charge density functional tight-binding (SCC-DFTB) method. This approach allows one to explore the parameter space in a systematic fashion in order to find optimal solutions. We find that due to the limited flexibility of the SCC-DFTB electronic part, not all properties can be optimized simultaneously. For example, the optimization of heats of formation is in conflict with the optimization of vibrational frequencies. Therefore, a special parametrization, for vibrational frequencies is derived. It is shown that the performance of SCC-DFTB can be significantly improved using a more elaborate fitting strategy. A new fit for C and H is presented, which results in an average error of 2.6 kcal/mol for heats of formations for a large set of hydrocarbons, indicating that the performance of SCC-DFTB can be systematically improved also for other elements.
一部の光照射野において二次制御が可能なバックライトモジュールを形成する光学装置
(2009-10-29)
田仲豪
;
陸彦行
;
鄭裕國
;
呂柏毅
【課題】一部の光照射野において二次制御が可能なバックライトモジュールを形成する光学装置である。【解決手段】本発明は一部の光照射野において二次制御が可能なバックライトモジュールに関する光学装置である。まず、導光板は複数の導光エレメントを有し、当該導光エレメントには中央の穴と、導光板光入射面と、一導光板光出射面と、導光板底面とを有する点光源を備え、当該点光源は当該導光エレメントの中央の穴に位置し、導光板底面には複数のマイクロ構造体を備えている。集光膜シートは、複数の照射膜エレメントを有し、当該照射膜エレメント上の集光膜光出射面には複数のマイクロ構造体を備え、当該マイクロ構造体により、照射膜エレメントと導光エレメントを接合することで、一部の光照射野において二次制御が可能なバックライトモジュール装置を形成する。【選択図】図３－Ｂ
Quantum Chemical Prediction of Pathways; and Rate Constants for Reactions of CO and CO2 with Vacancy Defects on Graphite (0001) Surfaces
(2009-10-29)
Xu, S. C.
;
Irle, S.
;
Musaev, D. G.
;
Lin, M. C.
;
應用化學系分子科學碩博班
We present reaction pathways for adsorption of CO and CO2 molecules in the vicinity of monovacancy defects on graphite (0001) based on B3LYP and dispersion-augmented density-functional tight-binding (DFTB-D) studies of the potential energy surfaces (PES) of these reactions. To model the graphite (0001) monovacancy defects, finite-size molecular model systems up to the size of dicircumcoronene (C95H24) were employed. We find that the CO molecule reacts readily with the monovacancy defects and partially "heals" the carbon hexagon network leading to the formation of a stable epoxide, whereas CO2 oxidizes the defect via a dissociative adsorption pathway following CO elimination. We predict reaction rate constants in the temperature range between 300 and 3000 K using Rice-Ramsperger-Kassel-Marcus theory. Quantum chemical molecular dynamics simulations at 3000 K based on on-the-fly DFTB-D energies and gradients-support the results of our PES studies.
Quantum Chemical Prediction of Pathways; and Rate Constants for Reactions of CO and CO(2) with Vacancy Defects on Graphite (0001) Surfaces
(2009-10-29)
Xu, S. C.
;
Irle, S.
;
Musaev, D. G.
;
Lin, M. C.
;
應用化學系分子科學碩博班
We present reaction pathways for adsorption of CO and CO(2) molecules in the vicinity of monovacancy defects on graphite (0001) based on B3LYP and dispersion-augmented density-functional tight-binding (DFTB-D) studies of the potential energy surfaces (PES) of these reactions. To model the graphite (0001) monovacancy defects, finite-size molecular model systems up to the size of dicircumcoronene (C(95)H(24)) were employed. We find that the CO molecule reacts readily with the monovacancy defects and partially "heals" the carbon hexagon network leading to the formation of a stable epoxide, whereas CO(2) oxidizes the defect via a dissociative adsorption pathway following CO elimination. We predict reaction rate constants in the temperature range between 300 and 3000 K using Rice-Ramsperger-Kassel-Marcus theory. Quantum chemical molecular dynamics simulations at 3000 K based on on-the-fly DFTB-D energies and gradients-support the results of our PES studies.
統合型画像監視システムおよびその画像ビデオ融合方法
(2009-10-29)
陳永昇
;
鄭詠成
;
林開印
【課題】１つの領域の複数のカメラで取得したビデオを1つの大きな範囲の画像に統合し、1つの領域を監視する統合型画像監視システムを提供する。【解決手段】前記システムは、第１撮影装置と、第２撮影装置と、第３撮影装置と、画像処理装置と、表示装置とを主に含む。画像処理装置は、第１定義素子と、第１合成素子と、第２定義素子と、調整素子と、転換素子と、第３定義素子と、第２合成素子とをさらに含む。【選択図】図２
光検出装置構造
(2009-10-29)
孟心飛
;
洪勝富
;
趙宇強
【課題】光検出装置構造を提供する。【解決手段】光検出装置構造であって、基材と、垂直駆動有機発光トランジスタと、光検出ユニットとを含み、垂直駆動有機発光トランジスタは基材の第１位置に設置され、光検出ユニットは基材の第２位置に設置され、且つ設計上の需要に応じて第１位置と第２位置に所定の距離を隔てることができる。本光検出装置構造は、垂直駆動有機発光トランジスタによって光線を物体に発射し、光検出ユニットが物体により反射された反射光線を受信し、受信した反射光線を分析し、光検出装置構造と物体との間の距離を計算することに用いることができ、物体の形状または組成成分を判読することに用いることができる。【選択図】図１
TRANSIENT DETECTION CIRCUIT
(2009-10-29)
Ker, Ming-Dou
;
Yen, Cheng-Cheng
;
Liao, Chi-Sheng
;
Chen, Tung-Yang
A transient detection circuit coupled between a first power line and a second power line and including a first control unit, a setting unit, and a voltage regulation unit. The first control unit generates a first control signal. The first control signal is at a first level when an electrostatic discharge (ESD) event occurs. The first control signal is at a second level when the ESD event does not occur. The setting unit sets a first node. The first node is set at the second level when the first control signal is at the first level. The voltage regulation unit regulates the first node. The voltage regulation unit regulates the level of the first node at the second level when the first control signal is at the second level.
Thickness Dependent Phase Behavior of Antiferroelectric Liquid Crystal Films
(2009-10-30)
Pan, LiDong
;
Wang, Shun
;
Hsu, C. S.
;
Huang, C. C.
;
應用化學系
Free standing films of a liquid crystal compound with simple surface enhanced order were studied. The resultant phase diagram demonstrates that (1) the short helical pitch smectic-C-alpha* phase disappears below a film thickness of 10 layers, and (2) the temperature window of a distorted 4 layer smectic-C-FI2* phase increases dramatically upon decreasing film thickness. The experimental findings were attributed to the reduced dimensionality and enhanced surface effects in thin films. The results of the smectic-C-alpha* phase are consistent with what have been reported for helically ordered magnetic thin films, with a noticeable difference due to the opposite effect of the surface on ordering in the two systems.
Chaos synchronization and chaotization of complex chaotic systems in series form by optimal control
(2009-10-30)
Ge, Zheng-Ming
;
Yang, Cheng-Hsiung
;
機械工程學系
;
Department of Mechanical Engineering
By the method of quadratic optimum control, a quadratic optimal regulator is used for synchronizing two complex chaotic systems in series form. By this method the least error with less control energy is achieved, and the optimization on both energy and error is realized synthetically. The simulation results of two Quantum-CNN chaos systems in series form prove the effectiveness of this method. Finally, chaotization of the system is given by optimal control. (C) 2009 Elsevier Ltd. All rights reserved.
(PS)(2)-v2: template-based protein structure prediction server
(2009-10-31)
Chen, Chih-Chieh
;
Hwang, Jenn-Kang
;
Yang, Jinn-Moon
;
生物科技學系
;
生物資訊及系統生物研究所
Background: Template selection and target-template alignment are critical steps for template-based modeling (TBM) methods. To identify the template for the twilight zone of 15 similar to 25% sequence similarity between targets and templates is still difficulty for template-based protein structure prediction. This study presents the (PS)(2)-v2 server, based on our original server with numerous enhancements and modifications, to improve reliability and applicability. Results: To detect homologous proteins with remote similarity, the (PS)(2)-v2 server utilizes the S2A2 matrix, which is a 60 x 60 substitution matrix using the secondary structure propensities of 20 amino acids, and the position-specific sequence profile (PSSM) generated by PSI-BLAST. In addition, our server uses multiple templates and multiple models to build and assess models. Our method was evaluated on the Lindahl benchmark for fold recognition and ProSup benchmark for sequence alignment. Evaluation results indicated that our method outperforms sequence-profile approaches, and had comparable performance to that of structure-based methods on these benchmarks. Finally, we tested our method using the 154 TBM targets of the CASP8 (Critical Assessment of Techniques for Protein Structure Prediction) dataset. Experimental results show that (PS)(2)-v2 is ranked 6(th) among 72 severs and is faster than the top-rank five serves, which utilize ab initio methods. Conclusion: Experimental results demonstrate that (PS)(2)-v2 with the S2A2 matrix is useful for template selections and target-template alignments by blending the amino acid and structural propensities. The multiple-template and multiple-model strategies are able to significantly improve the accuracies for target-template alignments in the twilight zone. We believe that this server is useful in structure prediction and modeling, especially in detecting homologous templates with sequence similarity in the twilight zone.
Effects of a Modulated Electric Field on the Optical Absorption Spectra in a Single-Layer Graphene
(2009-11-01)
Chiu, Yu-Huang
;
Ho, Jon-Hsu
;
Ho, Yen-Hung
;
Chuu, Der-San
;
Lin, Ming-Fa
The optical absorption spectra of a graphene monolayer in the presence of a modulated electric field are investigated by the gradient approximation with tight-binding model. Such a field could strongly affect the low-energy electronic and optical properties. The low-energy bands exhibit two kinds of band-edge states (mu and nu), which lead to many prominent asymmetric peaks in the density of states (DOS). The finite DOS at omega = 0 implies that a single layer graphene in the presence of modulated electric fields would become a semimetallic one. The low-frequency optical absorption spectra display rich peaks and they vanish at omega = 0. Such absorption peaks mainly result from the two kinds of band-edge states and could be divided into two groups. However, they could not be ascribed to an obvious selection rule. It is worth noting that the optical absorption spectra could show anisotropic features in different modulated directions. The predicted results could be verified by the experimental measurements.
Process and properties of the carbon nanotube assisted LiCoO(2) thin-film battery electrode by pulsed laser deposition
(2009-11-01)
Lo, An-Ya
;
Sun, Chuan-Shu
;
Tseng, Wen-Shou
;
Kuo, Cheng-Tzu
;
材料科學與工程學系
In this study, a pulsed laser deposition process was developed to deposit a carbon nanotube (CNT) assisted LiCoO(2) electrode to improve its power density. The electrodes were deposited on Pt-coated Si substrates with Ar and O(2) as sputtering gases and LiCoO(2)+C as the target. The results indicate that the working pressure is the most important parameter to control the composition of the electrode. Therefore, electrodes with a three-layer structure (i.e., LiCoO(2)-rich/CNT-rich/LiCoO(2)-rich) were fabricated by a three-step deposition process by varying the pressures from 13 to 1.3x10(4) Pa and then 13 Pa again, and it was found that the charge/discharge capacity became approximately 1.5 times greater than that in the corresponding electrode without a CNT-rich layer. The results also indicate that a higher substrate temperature is favorable for improving the crystallinity of the electrode to approach LiCoO(2) crystals.
Fault-Tolerant Hamiltonian Connectivity and Fault-Tolerant Hamiltonicity of the Fully Connected Cubic Networks
(2009-11-01)
Ho, Tung-Yang
;
Lin, Cheng-Kuan
;
資訊工程學系
;
Department of Computer Science
Many papers on the fully connected cubic networks have been published for the past several years due to its favorite properties. In this paper, we consider the fault-tolerant hamiltonian connectivity and fault-tolerant hamiltonicity of the fully connected cubic network. We use FCCN(n) to denote the fully connected cubic network of level n. Let G = (V, E) be a graph. The fault-tolerant hamiltonian connectivity H(f)(k) (G) is defined to be the maximum integer l such that G - F remains hamiltonian connected for every F subset of V(G) boolean OR E(G) with vertical bar F vertical bar <= l. The fault-tolerant hamiltonicitly H(f)(G) is defined to be the maximum integer l such that G - F remains hamiltonian for every F subset of V(G) boolean OR E(G) with vertical bar F vertical bar <= l. We prove that H(f)(k) (FCCN(n)) = 0 and H(f)(FCCN(n)) = 1 if n >= 2.