Browsing by Issue Date, starting with "2009-04-13"

Now showing 1 - 20 of 50951

Time-division-multiplexing using pulse position locking for 100 Gb/s applications
(2009-04-13)
Chow, C. W.
;
Ellis, A. D.
;
Parmigiani, F.
;
光電工程學系
;
Department of Photonics
Recently, there is a great interest in pushing communication technologies to 100 Gb/s. However, there are still many challenges to perform high speed (> 40 Gb/s) clock and data recovery, and data time-division-multiplexing (TDM). Here, we propose and numerically analyze an asynchronous optical packet retimer using parabolic or sinusoidal phase modulation and linear dispersion. This scheme is named pulse position locking (PPL). Numerical simulation shows that this scheme can effectively resynchronize input signals with arbitrary delays to the local clock, and reduce input jitter. The scheme can also be applied to TDM 10 Gb/s and 40 Gb/s signals to over 100 Gb/s. (C) 2009 Optical Society of America
Magnetophotoluminescence properties of Co-doped ZnO nanorods
(2009-04-13)
Lin, C. Y.
;
Wang, W. H.
;
Lee, C. -S.
;
Sun, K. W.
;
Suen, Y. W.
We present the detailed experimental results of the magnetic and optical properties of cobalt doped ZnO nanorods, especially the temperature and magnetic field dependence of photoluminescence up to 14 T. The Raman measurements indicate that our Co-doped ZnO nanorods have the same lattice constant as crystalline bulk ZnO. Sharp luminescence peaks centered at around 670 nm were observed at low temperature and their intensity decreased with increasing magnetic field. The luminescence peaks were attributed to d-d transitions in the Ligand field from the doped Co ions. We also observed a diamagnetic shift at a temperature of 1.5 K when the magnetic field was scanned from 0 to 14 T. The exciton radius of the Co-doped ZnO nanorods was deduced from the magnetophotoluminescence results.
Matrix reorganization with intramolecular tunneling of H atom: Formic acid in Ar matrix
(2009-04-14)
Trakhtenberg, Leonid I.
;
Fokeyev, Anatoly A.
;
Zyubin, Alexander S.
;
Mebel, Alexander M.
;
Lin, S. H.
The intramolecular tunneling of hydrogen atom in formic acid HCOOH at low temperatures is considered based on literature experimental data on C-O internal rotation. The energetic and geometric parameters as well as vibrational frequencies for formic acid in cis and trans configurations surrounded by 12 Ar atoms are calculated in the frame of the MP2 approach with extended basis sets. The temperature and pressure dependence of the rate constant is analyzed taking into consideration the matrix reorganization for the Debye model of lattice motion. It has been shown that the available experimental data can be explained by the suggested matrix reorganization mechanism. Theoretical expressions for the temperature dependence of the rate constant agree well with the experimental data on the cis to trans tunneling reactions in formic acid with fitting parameters attaining reasonable values. A mechanism describing pressure dependence of the rate constant for H-atom intramolecular tunneling reactions is also proposed.
All-optical 2R regenerator using self-seeded laser diode
(2009-04-14)
Chi
;
Sien
;
Lee
;
Chien-Chung
;
Chien
The present invention is a self-seeded laser diode. The laser diode obtains a gain by itself without using expansive erbium-doped fiber amplifiers. Hence, the cost is reduced and the system is simplified.
Soluble Narrow-Band-Gap Copolymers Containing Novel Cyclopentadithiophene Units for Organic Photovoltaic Cell Applications
(2009-04-15)
Li, Kuang-Chieh
;
Hsu, Ying-Chan
;
Lin, Jiann-T'suen
;
Yang, Chang-Chung
;
Wei, Kung-Hwa
Five novel conjugated copolymers (P1-P5) containing coplanar cyclopentadithiophene (CPDT) units (incorporated with arylcyanovinyl and keto groups in different molar ratios) were synthesized and developed for the applications of polymer solar cells (PSCs). Polymers P1-P5 covered broad absorption ranges from U-V to near infrared (400-900 nm) with narrow optical band gaps of 1.38-1.70 eV, which are compatible with the maximum solar photon reflux. Partially reversible p- and n-doping processes of P1-P5 in electrochemical experiments were observed, and the proper molecular design for highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) levels of P1-P5 induced the highest photovoltaic open-circuit voltage in the PSC devices, compared with those previously reported CPDT-based narrow-band-gap polymers. Powder X-ray diffraction (XRD) analyses suggested that these copolymers formed self-assembled pi-pi stacking and pseudobilayered structures. Under 100 mW/cm(2) of AM 1.5 white-light illumination, bulk hetero-junction PSC devices containing an active layer of electron donor polymers P1-P5 mixed with electron acceptor [6,6]-phenyl C(61) butyric acid methyl ester (PCBM) in the weight ratio of 1:4 were investigated. The PSC device containing P1 gave the best preliminary result with an open-circuit voltage of 0.84 V, a short-circuit current of 2.36 mA/cm(2), and a fill factor of 0.38, offering an overall power conversion efficiency (PCE) of 0.77% as well as a maximal quantum efficiency of 23% from the external quantum efficiency (EQE) measurements. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2073-2092, 2009
Corrosion behaviors of austenitic Fe-30Mn-7Al-xCr-1C alloys in 3.5% NaCl solution
(2009-04-15)
Tuan, Y. H.
;
Wang, C. S.
;
Tsai, C. Y.
;
Chao, C. G.
;
Liu, T. F.
The corrosion behaviors of the as-quenched Fe-30wt.%Mn-7wt.%Al-xwt.%Cr-1 wt.%C alloys (x = 0, 3, 6 and 9) in 3.5% NaCl have been investigated. Passivation could be observed for all the alloys except for the alloy without Cr content. The corrosion potential (E(corr)) and pitting potential (E(pp)) increased pronouncedly with increasing Cr content up to 6 wt.%, and decreased as Cr content up to 9 wt.%. The decrease of E(corr) and E(pp) of the alloy containing 9 wt.% Cr was due to the formation of (Fe,Mn,Cr)(7)C(3) carbides in the austenite matrix and on the grain boundaries. It is noted that the corrosion behaviors of the austenitic Fe-Mn-Al-Cr-C alloys with higher Cr(>= 3 wt.%) content have never been reported in previous literatures. (C) 2008 Elsevier B.V. All rights reserved.
Surface Modification of Gold Nanoparticles with Polyhedral Oligomeric Silsesquioxane and Incorporation within Polymer Matrices
(2009-04-15)
Kuo, Shiao-Wei
;
Wu, Yung-Chien
;
Lu, Chu-Hua
;
Chang, Feng-Chih
;
應用化學系
A new approach to achieve polymer-mediated gold ferromagnetic nanocomposites in a polyhedral oligomeric silsesquioxane (POSS)-containing random copolymer matrix has been developed. Stable and narrow distributed gold nanoparticles modified by 3-mercaptopropylisobutyl POSS to form Au-POSS nanoparticles are prepared by two-phase liquid-liquid method. These Au-POSS nanoparticles form partial particle aggregation by blending with poly(n-butyl methacrylate) (PnBMA) homopolymer because of poor miscibility between Au-POSS and PnBMA polymer matrix. The incorporation the POSS moiety into the PnBMA main chain as a random copolymer matrix displays well-dispersed gold nanoparticles because the POSS-POSS interaction enhances miscibility between gold nanoparticles and the PnBMA-POSS copolymer matrix. This gold-containing nanocomposite exhibits ferromagnetic phenomenon at room temperature. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 811-819, 2009
A simple Proof for persistence of snap-back repellers
(2009-04-15)
Li, Ming-Chia
;
Lyu, Ming-Jiea
;
應用數學系
;
Department of Applied Mathematics
In this article, we show that if f has a snap-back repeller then any small C(1) perturbation of f has a snap-back repeller, and hence has Li-Yorke chaos and positive topological entropy, by simply using the implicit function theorem. We also give some examples. (C) 2008 Elsevier Inc. All rights reserved.
Synthesis of La0.6Ca0.4Co0.8Ir0.2O3 perovskite for bi-functional catalysis in an alkaline electrolyte
(2009-04-15)
Chang, Yun-Min
;
Wu, Pu-Wei
;
Wu, Cheng-Yeou
;
Hsieh, Yu-Chi
;
材料科學與工程學系
The amorphous citrate precursor method was employed to prepare perovskite of La0.6Ca0.4Co0.8Ir0.2O3 as a bi-functional electrocatalyst for oxygen reduction and evolution in an alkaline electrolyte. The X-ray diffraction pattern of the as-synthesized powders exhibited a majority phase identical to that of La0.6Ca0.4CoO3, indicating successful incorporation of Ir4(+) at the Co cation sites. Scanning Electron Microscope images demonstrated a foam-like microstructure with a surface area of 13.31 m(2) g(-1). For electrochemical characterization, the La0.6Ca0.4CO0.8Ir0.2O3 particles were supported on carbon nanocapsules (CNCs) and deposited on commercially available gas diffusion electrodes with a loading of 2.4 mg cm(-2). In current- potential polarizations, La0.6Ca0.4Co0.8Ir0.2O3/CNCs revealed more enhanced bifunctional catalytic abilities than La0.6Ca0.4CoO3/CNCs. Similar behaviors were observed in galvanostatic profiles for oxygen reduction and evolution at current densities of 50 and 100mAcm(-2) for 10 min. Moreover, notable changes from zeta potential measurements were recorded for La0.6Ca0.4Co0.08Ir0.02O3 relative to La0.06Ca0.4CoO3, In lifetime determinations, where a repeated 3 h sequence of oxygen reduction/resting/oxygen evolution/resting was imposed, La0.6Ca0.4Co0.8Ir0.2O3/CNCs delivered a stable and sustainable behavior with moderate degradation. (C) 2008 Elsevier B.V. All rights reserved.
Inner functions of numerical contractions
(2009-04-15)
Gau, Hwa-Long
;
Wu, Pei Yuan
;
應用數學系
;
Department of Applied Mathematics
We prove that, for a function f in H(infinity) of the unit disc with parallel to f parallel to(infinity) <= 1, the existence of an operator T on a complex Hilbert space H with its numerical radius at most one and with parallel to f(T)x parallel to = 2 for some unit vector x in H is equivalent to that f be an inner function with f (0) = 0. This confirms a conjecture of Drury [S.W. Drury, Symbolic calculus of operators with unit numerical radius, Linear Algebra Appl. 428 (2008) 2061-2069]. Moreover, we also show that any operator T satisfying the above conditions has a direct summand similar to the compression of the shift S(phi), where phi(z) = zf(z) for vertical bar z vertical bar < 1. This generalizes the result of Williams and Crimmins [J.P. Williams, T. Crimmins, On the numerical radius of a linear operator, Amer. Math. Monthly 74 (1967) 832-833] for f (z) = z and of Crabb [M.J. Crabb, The powers of an operator of numerical radius one, Michigan Math. J. 18 (1971) 253-256] for f(z) = z(n) (n >= 2). (C) 2008 Elsevier Inc. All rights reserved.
Synthesis of La(0.6)Ca(0.4)Co(0.8)Ir(0.2)O(3) perovskite for bi-functional catalysis in an alkaline electrolyte
(2009-04-15)
Chang, Yun-Min
;
Wu, Pu-Wei
;
Wu, Cheng-Yeou
;
Hsieh, Yu-Chi
;
材料科學與工程學系
The amorphous citrate precursor method was employed to prepare perovskite of La(0.6)Ca(0.4)Co(0.8)Ir(0.2)O(3) as a bi-functional electrocatalyst for oxygen reduction and evolution in an alkaline electrolyte. The X-ray diffraction pattern of the as-synthesized powders exhibited a majority phase identical to that of La(0.6)Ca(0.4)CoO(3), indicating successful incorporation of Ir4(+) at the Co cation sites. Scanning Electron Microscope images demonstrated a foam-like microstructure with a surface area of 13.31 m(2) g(-1). For electrochemical characterization, the La(0.6)Ca(0.4)CO(0.8)Ir(0.2)O(3) particles were supported on carbon nanocapsules (CNCs) and deposited on commercially available gas diffusion electrodes with a loading of 2.4 mg cm(-2). In current- potential polarizations, La(0.6)Ca(0.4)Co(0.8)Ir(0.2)O(3)/CNCs revealed more enhanced bifunctional catalytic abilities than La(0.6)Ca(0.4)CoO(3)/CNCs. Similar behaviors were observed in galvanostatic profiles for oxygen reduction and evolution at current densities of 50 and 100mAcm(-2) for 10 min. Moreover, notable changes from zeta potential measurements were recorded for La(0.6)Ca(0.4)Co(0.08)Ir(0.02)O(3) relative to La(0.06)Ca(0.4)CoO(3), In lifetime determinations, where a repeated 3 h sequence of oxygen reduction/resting/oxygen evolution/resting was imposed, La(0.6)Ca(0.4)Co(0.8)Ir(0.2)O(3)/CNCs delivered a stable and sustainable behavior with moderate degradation. (C) 2008 Elsevier B.V. All rights reserved.
Distribution of Vibrational States of CO(2) in the Reaction O((1)D) + CO(2) from Time-Resolved Fourier Transform Infrared Emission Spectra
(2009-04-16)
Chen, Hui-Fen
;
Chiang, Hung-Chu
;
Matsui, Hiroyuki
;
Tsuchiya, Soji
;
Lee, Yuan-Pern
A mixture Of O(3) and CO(2) was irradiated with light from a KrF laser at 248 nm; time-resolved infrared emission Of CO(2) in the region 2000-2400 cm(-1) was observed with a Fourier transform spectrometer. This emission involves one quantum in the asymmetric stretching mode (nu(3)) Of CO(2) in highly vibrationally excited states. The band contour agrees satisfactorily with a band shape calculated based on a simplified polyad model of CO(2) and a vibrational distribution estimated through a statistical partitioning of energy of similar to 13 000 cm(-1), similar to 3100 cm(-1) smaller than the available energy, into the vibrational modes Of CO(2). From this model, approximately 44% and 5% of the available energy of O((1)D) + CO(2) is converted into the vibrational and rotational energy of product CO(2), respectively, consistent with previous reports of similar to 50% for the translational energy. An extent of rotational excitation Of CO(2) much smaller than that expected from statistical calculations indicates a mechanism that causes a small torque to be given to CO(2) when an O atom leaves the complex CO(3) on the triplet exit surface of potential energy, consistent with quantum-chemical calculations.
Method for forming III-nitrides semiconductor epilayer on the semiconductor substrate
(2009-04-16)
Chang, Chun-Yen
;
Yang, Tsung-Hsi
;
Shen, Shih-Guo
GaN layer on semiconductor substrate is grown by using GaN nanorod buffer layer. Firstly, semiconductor substrate is cleaned and thermally degassed to remove the contaminant in the growth chamber. After the above step, the GaN nanorods layer is grown under the N-rich condition. Then, GaN epilayer is overgrown on the GaN nanorods layer under the Ga-rich condition for forming Group of III-Nitrides semiconductor layer on the semiconductor substrate.
於半導體基板上形成三族氮化物半導體層的方法
(2009-04-16)
張俊彥
;
楊宗
;
沈詩國
本發明為一種於半導體基板上形成三族氮化物半導體層的方法。首先,提供一半導體基板,其半導體基板上具有一清潔表面;再形成一氮化鎵奈米柱緩衝層;覆蓋成長形成一氮化鎵磊晶層於氮化鎵奈米柱緩衝層上,藉以形成三族氮化物半導體層於半導體基板上。
Adsorption Configurations and Reactions of Nitric Acid on TiO(2) Rutile (110) and Anatase (101) surfaces
(2009-04-16)
Chang, Ching Yi
;
Chen, Hsin-Tsung
;
Lin, M. C.
;
應用化學系分子科學碩博班
;
Institute of Molecular science
The adsorption and reactions of the monomer and dimer of nitric acid on TiO(2) rutile (110) and anatase (101) surfaces have been studied by first-principles density functional theory with ultrasoft pseudopotential approximation. The most stable configuration of HNO(3) on the rutile surface is a molecular monodentate adsorbed on the 5-fold coordinated Ti atom with the hydrogen bonded to a neighboring surface bridging oxygen with the adsorption energy of 6.7 kcal/mol. It can dissociate its H atom to a nearest bridged oxygen with almost no barrier to produce NO(3)(a) + H(a). The rotation of NO(3) requires a barrier of 12.2 kcal/mol to form the didentate configuration, Ti(5c)-ON(O)-Ti(5c)H-O(2),(a), which adsorbs on two 5-fold coordinated Ti atoms with the adsorption energy of 16.5 kcal/mol. In the case of the adsorption of 2HNO(3) molecules, the most stable configuration, 2(Ti(5c)-ON(O)OH...O(2c)(a)), has a structure similar to two single HNO(3) adsorbates on two 5-fold coordinated Ti atoms with the adsorption energy of 12.8 kcal/mol, which is about twice that of the single HNO(3) molecule. The result suggests that the interaction of the two planar HNO(3) adsorbates is negligible. The dehydration from 2(Ti(5c)-ON(O)OH...O(2)c(a)) forming N(2)O(5)(a) + H(2)O(a) requires an energy barrier of 46.2 kcal/mol, indicating that the dimerization of the two HNO(3)(a) is difficult. Similar adsorption phenomena appear on the anatase (101) surface. In addition, we find that the coadsorption of hydrogen plays a significant role in the adsorption energies of adsorbates, especially for the NO(3) radical, which may be employed as a linker between semiconductor quantum dots such as InN and the TiO(2) surface.
可預測均流程度之斜率控制裝置及其方法
(2009-04-16)
何心欣
;
陳科宏
;
謝俊禹
本發明係揭露一種可預測均流程度之斜率控制裝置及其方法,其可應用於一冗餘或分散式的電源供應系統中,並達到更佳的負載電流分配效果。本發明之裝置包括一轉導放大電路、一斜率調整電路及一電壓遞增電路。本發明利用一轉導參數改善輸出電壓對於輸出電流之斜率,以及利用轉導參數使分散式的電源供應系統中諸電源供應模組具有較佳之相同斜率。本發明更包括動態拉升輸出電壓使輸出電流步進提升,進而達到系統所能承受之範圍。
Distribution of Vibrational States of CO2 in the Reaction O(D-1) + CO2 from Time-Resolved Fourier Transform Infrared Emission Spectra
(2009-04-16)
Chen, Hui-Fen
;
Chiang, Hung-Chu
;
Matsui, Hiroyuki
;
Tsuchiya, Soji
;
Lee, Yuan-Pern
A mixture Of O-3 and CO2 was irradiated with light from a KrF laser at 248 nm; time-resolved infrared emission Of CO2 in the region 2000-2400 cm(-1) was observed with a Fourier transform spectrometer. This emission involves one quantum in the asymmetric stretching mode (nu(3)) Of CO2 in highly vibrationally excited states. The band contour agrees satisfactorily with a band shape calculated based on a simplified polyad model of CO2 and a vibrational distribution estimated through a statistical partitioning of energy of similar to 13 000 cm(-1), similar to 3100 cm(-1) smaller than the available energy, into the vibrational modes Of CO2. From this model, approximately 44% and 5% of the available energy of O(D-1) + CO2 is converted into the vibrational and rotational energy of product CO2, respectively, consistent with previous reports of similar to 50% for the translational energy. An extent of rotational excitation Of CO2 much smaller than that expected from statistical calculations indicates a mechanism that causes a small torque to be given to CO2 when an O atom leaves the complex CO3 on the triplet exit surface of potential energy, consistent with quantum-chemical calculations.
Adsorption Configurations and Reactions of Nitric Acid on TiO2 Rutile (110) and Anatase (101) surfaces
(2009-04-16)
Chang, Ching Yi
;
Chen, Hsin-Tsung
;
Lin, M. C.
;
應用化學系分子科學碩博班
;
Institute of Molecular science
The adsorption and reactions of the monomer and dimer of nitric acid on TiO2 rutile (110) and anatase (101) surfaces have been studied by first-principles density functional theory with ultrasoft pseudopotential approximation. The most stable configuration of HNO3 on the rutile surface is a molecular monodentate adsorbed on the 5-fold coordinated Ti atom with the hydrogen bonded to a neighboring surface bridging oxygen with the adsorption energy of 6.7 kcal/mol. It can dissociate its H atom to a nearest bridged oxygen with almost no barrier to produce NO3(a) + H(a). The rotation of NO3 requires a barrier of 12.2 kcal/mol to form the didentate configuration, Ti-5c-ON(O)-Ti5cH-O-2,(a), which adsorbs on two 5-fold coordinated Ti atoms with the adsorption energy of 16.5 kcal/mol. In the case of the adsorption of 2HNO(3) molecules, the most stable configuration, 2(Ti-5c-ON(O)OH...O-2c(a)), has a structure similar to two single HNO3 adsorbates on two 5-fold coordinated Ti atoms with the adsorption energy of 12.8 kcal/mol, which is about twice that of the single HNO3 molecule. The result suggests that the interaction of the two planar HNO3 adsorbates is negligible. The dehydration from 2(Ti-5c-ON(O)OH...O(2)c(a)) forming N2O5(a) + H2O(a) requires an energy barrier of 46.2 kcal/mol, indicating that the dimerization of the two HNO3(a) is difficult. Similar adsorption phenomena appear on the anatase (101) surface. In addition, we find that the coadsorption of hydrogen plays a significant role in the adsorption energies of adsorbates, especially for the NO3 radical, which may be employed as a linker between semiconductor quantum dots such as InN and the TiO2 surface.
Using sweeping micellar electrokinetic chromatography to analyze Delta(9)-tetrahydrocannabinol and its major metabolites
(2009-04-17)
Su, Hsiu-Li
;
Feng, Lan-Ing
;
Jen, Hsiu-Ping
;
Hsieh, You-Zung
;
應用化學系
We have applied sweeping micellar electrokinetic chromatography (sweeping-MEKC) to the simultaneous determination of Delta(9)-tetrahydrocannabinol (THC) and its major metabolites, 11-hydroxy-Delta(9)-tetrahydrocannabinol (THC-OH) and 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH). We monitored the effects of several of the sweeping-MEKC parameters, including the proportion of organic modifier, the concentration of sodium dodecyl sulfate (SDS), the pH, and the sample injection volume, to optimize the separation process. The optimal buffer for the analysis of the three analytes was 25 mM citric acid/disodium hydrogenphosphate (pH 2.6) containing 40% methanol and 75 mM SDS. Under the optimized separation parameters, the enrichment factors for THC, THC-COOH, and THC-OH when using sweeping-MEKC (relative to MEKC) were 77,139, and 200, respectively. The limits of detection (LODs) for the three compounds in standard solutions ranged from 3.87 to 15.2 ng/mL. We combined the sweeping-MEKC method with solid-phase extraction to successfully detect THC, THC-COOH, and THC-OH in human urine with acceptable repeatability. The LODs of these analytes in urine samples ranged from 17.2 to 23.3 ng/mL. Therefore, this sweeping-MEKC method is useful for determining, with high sensitivity, the amounts of THC and its metabolites in the urine of suspected THC users. (C) 2008 Elsevier B.V. All rights reserved.
《千年狐》韓國動畫新里程
(2009-04-19)
陳妙寧
;
Department of Communication and Technology
;
傳播與科技學系
0