Browsing by Issue Date, starting with "2005-01-21"

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非等間隔取樣之快速褶積方法
(2005-01-21)
白明憲
;
曾平順
本發明係揭露一種非等間隔取樣之快速褶積方法，其係先輸入一待處理之數位訊號資料後，再分析欲與輸入訊號做摺積運算的原始濾波器特性做褶積運算的資料特性；並對此資料的脈衝響應及頻率響應分別進行非等間隔取樣，以得到一較短階數脈衝響應及一樣版函數；根據此樣版函數做最佳化設計，以求得較短階數脈衝響應之參數；最後再利用此較短階數脈衝響應之參數進行褶積運算，以模擬出近似於原始長階數脈衝響應所褶積之效果。因此，本發明在保留資料原本特性之前提下，直接以軟體做適當的壓縮與處理，用以減少運算量及增快運算速度，以達到即時處理大量資料之功效者。
Effect of the polyimide structure and ZnO concentration on the morphology and characteristics of polyimide/ZnO nanohybrid films
(2005-01-21)
Hsu, SC
;
Whang, WT
;
Hung, CH
;
Chiang, PC
;
Hsiao, KN
A series of polyimide/ZnO nanohybrid films with different ZnO content were prepared from a rigid pyromellitic dianhydride-4,4'-diaminodiphenyl ether (PMDA-ODA) polyimide (PI) and a flexible 3,3,4,4-benzophenonetetracarboxylic acid dianhydride-4,4'-diaminodiphenyl ether (BTDA-ODA) PI with ZnO nanoparticles (3-4 nm). Fourier-transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) depict that the ZnO nanoparticles function as a physical cross-linking agent with PI through hydrogen bonding between the OH on the ZnO nanoparticles and the C=O of the imide groups. ZnO nanoparticles in the rigid PMDA-ODA matrix cause a larger percentage decrease in the coefficient of linear thermal expansion (CTE) than in the flexible BTDA-ODA matrix. The BTDA-ODA/ZnO hybrid films have two transition peaks in dynamic mechanical tan curves, but PMDA-ODA/ZnO hybrid films only have one transition peak. Thermogravimetric analysis reveals that ZnO decreases the thermal degradation temperature (T-d) in both hybrid films, but less so in PMDA-ODA/ZnO films. Trans-mission electron microscopy (TEM) images reveal that the rigid matrix induces larger particle size (30-40 nm) compared to the flexible matrix (10-15 nm).
Modified polycrystalline silicon chemical-vapor deposition process for improving roughness at oxide/polycrystalline silicon interface
(2005-01-24)
Chang, JJ
;
Hsieh, TE
;
Wang, YL
;
Tseng, WT
;
Liu, CP
A new modified low pressure chemical-vapor deposition process for stacked polysilicon (poly-Si) films is developed in this study. The proposed stacked film process combines polysilicon with amorphous silicon films. In this process, polysilicon film was deposited first at 630degreesC, followed by a continuous temperature decrease down to 560degreesC for the deposition of amorphous silicon film. It was found that the doped stacked polysilicon films deposited by this process result in lowering of surface roughness, together with reduction of the (311) phase of the doped amorphous silicon and (110) phase of the doped polysilicon. As a consequence, device performance based on the stacked films also improves. Results of surface roughness analysis indicated that the doped stacked polysilicon film has a root-mean square surface roughness (Rrms) of 78 A, which is smaller than those of doped conventional (630degreesC) polysilicon film (Rrms=97 A), and doped amorphous silicon film (Rrms=123 A, deposited at 560degreesC). Transmission electron microscopic (TEM) observation performed at oxide/polysilicon interface showed that the conventional (630degreesC) oxide/polysilicon interface has high angle grain boundaries on the polysilicon side, which may induce leakage current around the interfacial area. (C) 2004 Elsevier B.V. All rights reserved.
Enhanced thermal properties of PS nanocomposites formed from montmorillonite treated with a surfactant/cyclodextrin inclusion complex
(2005-01-26)
Yei, DR
;
Kuo, SW
;
Fu, HK
;
Chang, FC
;
應用化學系
We have prepared polystyrene/clay nanocomposites using an emulsion polymerization technique. The nanocomposites were exfoliated at 3 wt% content of pristine clay relative to the amount of polystyrene (PS). We employed two surfactants for the montmorillonite: cetylpyridinium chloride (CPC) and the CPC/alpha-CD inclusion complex. Prior to polymerization, each surfactant intercalates into the layers of the pristine clay dispersed in water. The inclusion complex was characterized by X-ray diffraction, C-13 CP/MAS NMR spectra, and H-1 NMR spectroscopy, and TGA. X-ray powder patterns of the CPC/alpha-CD complex indicate that the alpha-CDs units form channels. The C-13 CP/MAS NMR spectrum of the complex suggests that a CPC chain is included in the channel formed by the alpha-CDs. The H-1 NMR spectra of the complexes indicate that the stoichiometry of the complexes is 1:2 (i.e. one CPC molecule and two alpha-CD units). The TGA reveals that the inclusion complex has higher thermal stability relative to the virgin CPC. We employed both X-ray diffraction (XRD) and transmission electron microscopy (TEM) to characterize the structures of the nanocomposites. The value of T-g of the PS component in the nanocomposite is 6degreesC higher than that of the virgin PS and its thermal decomposition temperature is 33degreesC higher. The CPC/alpha-CD-treated clay is more effective than is virgin CPC-treated clay at enhancing the thermal stability of polystyrene. (C) 2004 Published by Elsevier Ltd.
我是什麼東西，你不是東西
(2005-01-27)
管管
Syntheses, photoluminescence and electroluminescence of some new blue-emitting phosphorescent iridium(III)-based materials
(2005-01-27)
Laskar, IR
;
Hsu, SF
;
Chen, TM
;
應用化學系
;
Department of Applied Chemistry
The cyclometallated ligand 2-(4',6-difluorophenyl)-4-methoxypyridine (F(2)MeOppyH), whose complexes with iridium(III) emit bright blue to green light, was synthesized in five separate steps. Ir(F(2)MeOppy)(2)(acac), (acacH = 2,4-pentanedione), Ir(F(2)MeOppy)(2)(pic) (picH = 2-picolinic acid), fac-Ir(F(2)MeOppy)(3) and mer-lr(F(2)MeOppy)(3) complexes were synthesized from solution and fully characterized. The structures of Ir(F(2)MeOppy)(2)(acac) and fac-Ir(F(2)MeOppy)(3) were authenticated by X-ray single crystal structure analysis. fec-Ir(F(2)MeOppy)(3) showed a much higher solution photoluminescence (PL) quantum efficiency and blue-shifted emission compared to its counter mer-isomer. All of the complexes showed reversible oxidations between 0.3 and 0.7 V versus the ferrocene/ferrocenium ion. The relative thermodynamic stability of the mer versus fac isomer was investigated and correlated to their corresponding redox and PL properties. Two electroluminescent (EL) devices (D-1 and D-2) were fabricated using the same blue Ir(F(2)MeOppy)(2)(acac) complex as a a dopant but with two different hole blockers, BCP and BAlq, and consequently BCP proved itself a good hole blocker for this type of system. The fabrication of another EL device (D-3) was carried out by using the same dopant, only replacing the host CBP by a wider band gap host, mCP which showed improved luminance, luminance yield and power efficiency (D-2: 133 cd m(-2) 0.66 cd A(-1), 0.22 lm W-1; D-3: 326 cd m(-2); 1.63 cd A(-1); 0.26 lm W-1). (C) 2004 Elsevier Ltd. All rights reserved.
資深導演王正方出書宋岡陵現身站台
(2005-01-28)
黃文正
南亞賑災,藝文界人士明聯展義賣
(2005-01-28)
台北訊
53年日記本讓王正方哭了
(2005-01-28)
項貽斐
Path partition for graphs with special blocks
(2005-01-30)
Pan, JJ
;
Chang, GJ
;
應用數學系
;
Department of Applied Mathematics
The path-partition problem is to find a minimum number of vertex-disjoint paths that cover all vertices of a given graph. This paper studies the path-partition problem from an algorithmic point of view. As the Hamiltonian path problem is NP-complete for many classes of graphs, so is the path-partition problem. The main result of this paper is to present a linear-time algorithm for the path-partition problem in graphs whose blocks are complete graphs, cycles or complete bipartite graphs. (C) 2004 Elsevier B.V. All rights reserved.
Isometric-path numbers of block graphs
(2005-01-31)
Pan, JJ
;
Chang, GJ
;
應用數學系
;
Department of Applied Mathematics
An isometric path between two vertices in a graph G is a shortest path joining them. The isometric-path number of G, denoted by ip(G), is the minimum number of isometric paths required to cover all vertices of G. In this paper, we determine exact values of isometric-path numbers of block graphs. We also give a linear-time algorithm for finding the corresponding paths. (C) 2004 Elsevier B.V. All rights reserved.
Fluorene-based oxadiazoles: thermally stable electron-transporting materials for light-emitting devices
(2005-01-31)
Wu, FI
;
Shu, CF
;
Chien, CH
;
Tao, YT
;
應用化學系
We have synthesized and characterized a series of fluorene-based oxadiazole derivatives, in each of which two identical oxadiazole moieties are linked to a fluorene unit via an sp(3)-hybridized carbon atom (C-9) to form a rigid, nonplanar structure. This structural feature leads to a reduction in the tendency to crystallize and an increase in the glass transition temperature. Electrochemical studies revealed that these materials undergo reversible reductions and have high electron affinities. Each fluorene-based oxadiazole exhibited reasonably good performance when it was used as the electron-transporting layer in a multi-layer organic EL device. (C) 2004 Elsevier B.V. All rights reserved.
Applications of genetic algorithms in industry
(2005-02-01)
Wu, MC
;
Wortmann, H
;
Szirbik, N
;
交大名義發表
;
National Chiao Tung University
2 V-operated InGaP-AlGaAs-InGaAs enhancement-mode pseudomorphic HEMT
(2005-02-01)
Chu, LH
;
Chang, EY
;
Chen, SH
;
Lien, YC
;
Chang, CY
A low-voltage single power supply enhancement-mode InGaP-AlGaAs-InGaAs pseudomorphic high-electron mobility transistor (PHEMT) is reported for the first time. The fabricated 0.5 x 160 mum(2) device shows low knee voltage of 0.3 V, drain-source current (I-DS) of 375 mA/mm and maximum transconductance of 550 mS/mm when drain-source voltage (V-DS) was 2.5 V. High-frequency performance was also achieved; the cut-off frequency(F-t) is 60 GHz and maximum oscillation frequency(F-max) is 128 GHz. The noise figure of the 160-mum gate width device at 17 GHz was measured to be 1.02 dB with 10.12 dB associated gain. The E-mode InGaP-AlGaAs-InGaAs PHEMT, exhibits a high output power density of 453 mW/mm with a high linear gain of 30.5 dB at 2.4 GHz. The E-mode PHEMT can also achieve a high maximum power added efficiency (PAE) of 70%, when tuned for maximum PAE.
Study of air bearing with grooved disk surface in near-field optical disk drives
(2005-02-01)
Wang, HC
;
Liu, TS
;
Chang, CS
;
機械工程學系
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Department of Mechanical Engineering
To achieve stable flying height of a pickup head in near-field optical disk drives, the influence of disk grooves on the airflow of an air bearing deserves investigation, since at a very low flying height, groove geometry is comparable to the flying height. This paper aims to compare air bearing airflows between near-field optical disks with grooved surface and conventional disks without grooved surface. Computational results show that grooved disks generate smaller pressure than smooth disks since grooves can accommodate air molecules and tune air pressure. Flying higher makes pressure magnitudes closer between grooved disks and smooth disks in negative pressure area on slider bottoms. Further, track pitches and groove depths essentially do not affect pressure at rails.
Photocatalytic oxidation of gaseous DMF using thin film TiO2 photocatalyst
(2005-02-01)
Chang, CP
;
Chen, JN
;
Lu, MC
;
Yang, HY
;
環境工程研究所
The heterogeneous photocatalytic oxidation of gaseous N,N'-dimethylformamide (DMF) widely used in the manufacture of synthetic leather and synthetic textile was investigated. The experiments were carried out in a plug flow annular photoreactor coated with Degussa P-25 TiO2. The oxidation rate was dependent on DMF concentration, reaction temperature, water vapor, and oxygen content. Photocatalytic deactivation was observed in these reactions. The Levenspiel deactivation kinetic model was used to describe the decay of catalyst activity. Fourier transform infrared (FTIR) was used to characterize the surface and the deactivation mechanism of the photocatalyst. Results revealed that carbonylic acids, aldehydes, amines, carbonate and nitrate were adsorbed on the TiO2 surface during the photocatalytic reaction. The ions, NH4+ and NO3-, causing the deactivation of catalysts were detected on the TiO2 surface. Several treatment processes were applied to find a suitable procedure for the regeneration of catalytic activity. Among these procedures, the best one was found to be the H2O2/UV process. (C) 2004 Elsevier Ltd. All rights reserved.
Experimental realization of breaking diffraction limit by planar negative-index metamaterials in free space
(2005-02-01)
Lih, JS
;
Wang, YS
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Lu, MC
;
Huang, YC
;
Chen, KH
The sharpness of the image formed by a conventional lens is always limited by the wavelength of light. Recently, Pendry proposed a superlens, with a negative refractive index. such that the resolution is not limited by wavelength. Herein, we report direct experimental evidence of Pendry's superlens breaking the diffraction limit, in the microwave range of the X band (8-12 GHz), with a periodic array of split ring resonators and continuous wires; i.e. a meta-material with negative index of refraction.
濟南路上那棵玉蘭
(2005-02-01)
管管
Day-to-day vehicular flow dynamics in intelligent transportation network
(2005-02-01)
Cho, HJ
;
Hwang, MC
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
In this paper, a flow evolution model is developed by using the dynamical system approach for a vehicular network equipped with predicted travel information. The concerned system variables, path flow, and predicted minimal travel time of an origin-destination (OD) pair, are measured on the peak-hour-average base for each day. The time change rates of these two variables are formulated as a system of ordinary differential equations under the assumption of daily learning and adaptive processes for commuters. By incorporating the total perceived travel time loss (or saving) into the proposed models, time change rates of path flows are generated with a flow-related manner to prevent path flow dynamics from being insensible to traffic congestion which had been formulated in the existing studies. Heterogeneous models with various user adjusting sensitivities and predicted travel information are also presented. Equilibrium solutions of the proposed network dynamics satisfy the Wardrop user equilibria and are proved to be asymptotically stable by using the stability theorem of Lyapunov. The issue of existence and uniqueness of solutions is proved both on the lemma of Lipschitz condition and the fundamental theorem of ordinary differential equations. In addition, some simple examples are demonstrated to show the asymptotic behaviors of the proposed models numerically. (c) 2005 Elsevier Ltd. All rights reserved.
Parameter estimation for leaky aquifers using the extended Kalman filter, and considering model and data measurement uncertainties
(2005-02-01)
Yeh, HD
;
Huang, YC
;
環境工程研究所
;
Institute of Environmental Engineering
A method using the extended Kalman filter (EKF) is proposed to identify the hydraulic parameters in leaky aquifer systems both with and without considering the aquitard storage. In the case without considering the aquitard storage, Hantush and Jacob's model combined with EKF can optimally determine the parameters for the leaky aquifer when analyzing the drawdown data. Coupled with Neuman and Witherspoon's model, the EKF is also employed to estimate the four parameters of aquifers. The observed drawdown data may be either interpolated using the Lagrangian polynomial or recursively used while implementing the EKF. The proposed method can identify the parameters, using part of the interpolated drawdown data or recursively used data, and obtains results with good accuracy. In the field-pumping test, a long pumping time may not be necessary if the proposed method is implemented on a computer, which is connected to pressure transducers and a data logger. In the process of parameter estimation, the leakage coefficient changes marginally for the first few observations. This phenomenon reflects the fact that there is a time lag between the start of pumping and the leakage effect on the drawdown. The analyses of the data uncertainty demonstrate that the EKF approach is applicable for drawdown data even when it contains white noise or temporal correlated noise. Finally, the choice between Hantush and Jacob's model and Neuman and Witherspoon's model depends on the hydrogeological condition of the aquifer system indicated in the analyses of the model uncertainty. Hantush and Jacob's model is shown to be a good choice for representing the leaky aquifer system if, the aquitard storage is comparatively small. (C) 2004 Elsevier B.V. All rights reserved.